diff --git a/lib/coffee-script/browser.js b/lib/coffee-script/browser.js
index 39bde36aba..92f00509ca 100644
--- a/lib/coffee-script/browser.js
+++ b/lib/coffee-script/browser.js
@@ -50,7 +50,7 @@
             CoffeeScript.run(...param);
           }
         } else {
-          throw new Error("Could not load " + url);
+          throw new Error(`Could not load ${url}`);
         }
         if (callback) {
           return callback(param);
diff --git a/lib/coffee-script/cake.js b/lib/coffee-script/cake.js
index e1598c0b27..b73069735a 100644
--- a/lib/coffee-script/cake.js
+++ b/lib/coffee-script/cake.js
@@ -61,7 +61,7 @@
       options = oparse.parse(args);
     } catch (error) {
       e = error;
-      return fatalError("" + e);
+      return fatalError(`${e}`);
     }
     ref = options["arguments"];
     results = [];
@@ -76,13 +76,13 @@
     var cakefilePath, desc, name, relative, spaces, task;
     relative = path.relative || path.resolve;
     cakefilePath = path.join(relative(__originalDirname, process.cwd()), 'Cakefile');
-    console.log(cakefilePath + " defines the following tasks:\n");
+    console.log(`${cakefilePath} defines the following tasks:\n`);
     for (name in tasks) {
       task = tasks[name];
       spaces = 20 - name.length;
       spaces = spaces > 0 ? Array(spaces + 1).join(' ') : '';
-      desc = task.description ? "# " + task.description : '';
-      console.log("cake " + name + spaces + " " + desc);
+      desc = task.description ? `# ${task.description}` : '';
+      console.log(`cake ${name}${spaces} ${desc}`);
     }
     if (switches.length) {
       return console.log(oparse.help());
@@ -96,7 +96,7 @@
   };
 
   missingTask = function(task) {
-    return fatalError("No such task: " + task);
+    return fatalError(`No such task: ${task}`);
   };
 
   cakefileDirectory = function(dir) {
@@ -108,7 +108,7 @@
     if (parent !== dir) {
       return cakefileDirectory(parent);
     }
-    throw new Error("Cakefile not found in " + (process.cwd()));
+    throw new Error(`Cakefile not found in ${process.cwd()}`);
   };
 
 }).call(this);
diff --git a/lib/coffee-script/coffee-script.js b/lib/coffee-script/coffee-script.js
index fb425cf1b1..848cbe133c 100644
--- a/lib/coffee-script/coffee-script.js
+++ b/lib/coffee-script/coffee-script.js
@@ -107,17 +107,17 @@
       js += fragment.code;
     }
     if (options.header) {
-      header = "Generated by CoffeeScript " + this.VERSION;
-      js = "// " + header + "\n" + js;
+      header = `Generated by CoffeeScript ${this.VERSION}`;
+      js = `// ${header}\n${js}`;
     }
     if (generateSourceMap) {
       v3SourceMap = map.generate(options, code);
     }
     if (options.inlineMap) {
       encoded = base64encode(JSON.stringify(v3SourceMap));
-      sourceMapDataURI = "//# sourceMappingURL=data:application/json;base64," + encoded;
-      sourceURL = "//# sourceURL=" + ((ref1 = options.filename) != null ? ref1 : 'coffeescript');
-      js = js + "\n" + sourceMapDataURI + "\n" + sourceURL;
+      sourceMapDataURI = `//# sourceMappingURL=data:application/json;base64,${encoded}`;
+      sourceURL = `//# sourceURL=${(ref1 = options.filename) != null ? ref1 : 'coffeescript'}`;
+      js = `${js}\n${sourceMapDataURI}\n${sourceURL}`;
     }
     if (options.sourceMap) {
       return {
@@ -228,7 +228,7 @@
     fn1 = function(ext) {
       var base;
       return (base = require.extensions)[ext] != null ? base[ext] : base[ext] = function() {
-        throw new Error("Use CoffeeScript.register() or require the coffee-script/register module to require " + ext + " files.");
+        throw new Error(`Use CoffeeScript.register() or require the coffee-script/register module to require ${ext} files.`);
       };
     };
     for (i = 0, len = ref.length; i < len; i++) {
@@ -299,7 +299,7 @@
           return helpers.nameWhitespaceCharacter(errorText);
       }
     })();
-    return helpers.throwSyntaxError("unexpected " + errorText, errorLoc);
+    return helpers.throwSyntaxError(`unexpected ${errorText}`, errorLoc);
   };
 
   formatSourcePosition = function(frame, getSourceMapping) {
@@ -312,7 +312,7 @@
       if (frame.isEval()) {
         fileName = frame.getScriptNameOrSourceURL();
         if (!fileName) {
-          fileLocation = (frame.getEvalOrigin()) + ", ";
+          fileLocation = `${frame.getEvalOrigin()}, `;
         }
       } else {
         fileName = frame.getFileName();
@@ -321,7 +321,7 @@
       line = frame.getLineNumber();
       column = frame.getColumnNumber();
       source = getSourceMapping(fileName, line, column);
-      fileLocation = source ? fileName + ":" + source[0] + ":" + source[1] : fileName + ":" + line + ":" + column;
+      fileLocation = source ? `${fileName}:${source[0]}:${source[1]}` : `${fileName}:${line}:${column}`;
     }
     functionName = frame.getFunctionName();
     isConstructor = frame.isConstructor();
@@ -332,19 +332,19 @@
       if (functionName) {
         tp = as = '';
         if (typeName && functionName.indexOf(typeName)) {
-          tp = typeName + ".";
+          tp = `${typeName}.`;
         }
-        if (methodName && functionName.indexOf("." + methodName) !== functionName.length - methodName.length - 1) {
-          as = " [as " + methodName + "]";
+        if (methodName && functionName.indexOf(`.${methodName}`) !== functionName.length - methodName.length - 1) {
+          as = ` [as ${methodName}]`;
         }
-        return "" + tp + functionName + as + " (" + fileLocation + ")";
+        return `${tp}${functionName}${as} (${fileLocation})`;
       } else {
-        return typeName + "." + (methodName || '<anonymous>') + " (" + fileLocation + ")";
+        return `${typeName}.${methodName || '<anonymous>'} (${fileLocation})`;
       }
     } else if (isConstructor) {
-      return "new " + (functionName || '<anonymous>') + " (" + fileLocation + ")";
+      return `new ${functionName || '<anonymous>'} (${fileLocation})`;
     } else if (functionName) {
-      return functionName + " (" + fileLocation + ")";
+      return `${functionName} (${fileLocation})`;
     } else {
       return fileLocation;
     }
@@ -390,11 +390,11 @@
         if (frame.getFunction() === exports.run) {
           break;
         }
-        results.push("  at " + (formatSourcePosition(frame, getSourceMapping)));
+        results.push(`  at ${formatSourcePosition(frame, getSourceMapping)}`);
       }
       return results;
     })();
-    return (err.toString()) + "\n" + (frames.join('\n')) + "\n";
+    return `${err.toString()}\n${frames.join('\n')}\n`;
   };
 
 }).call(this);
diff --git a/lib/coffee-script/command.js b/lib/coffee-script/command.js
index f2b78392f9..6ebabeb160 100644
--- a/lib/coffee-script/command.js
+++ b/lib/coffee-script/command.js
@@ -107,7 +107,7 @@
         _ = match[0], name = match[1], module = match[2];
       }
       name || (name = helpers.baseFileName(module, true, useWinPathSep));
-      return name + " = require('" + module + "')";
+      return `${name} = require('${module}')`;
     }).join(';');
   };
 
@@ -121,7 +121,7 @@
     } catch (error) {
       err = error;
       if (err.code === 'ENOENT') {
-        console.error("File not found: " + source);
+        console.error(`File not found: ${source}`);
         process.exit(1);
       }
       throw err;
@@ -182,7 +182,7 @@
     ref1 = CoffeeScript.FILE_EXTENSIONS;
     for (i = 0, len = ref1.length; i < len; i++) {
       ext = ref1[i];
-      index = path.join(source, "index" + ext);
+      index = path.join(source, `index${ext}`);
       try {
         if ((fs.statSync(index)).isFile()) {
           return index;
@@ -194,7 +194,7 @@
         }
       }
     }
-    console.error("Missing index.coffee or index.litcoffee in " + source);
+    console.error(`Missing index.coffee or index.litcoffee in ${source}`);
     return process.exit(1);
   };
 
@@ -245,7 +245,7 @@
       if (CoffeeScript.listeners('failure').length) {
         return;
       }
-      message = (err != null ? err.stack : void 0) || ("" + err);
+      message = (err != null ? err.stack : void 0) || `${err}`;
       if (o.watch) {
         return printLine(message + '\x07');
       } else {
@@ -420,7 +420,7 @@
     if (!opts.join) {
       silentUnlink(outputPath(source, base));
       silentUnlink(outputPath(source, base, '.js.map'));
-      return timeLog("removed " + source);
+      return timeLog(`removed ${source}`);
     }
   };
 
@@ -481,21 +481,21 @@
           js = ' ';
         }
         if (generatedSourceMap) {
-          js = js + "\n//# sourceMappingURL=" + (helpers.baseFileName(sourceMapPath, false, useWinPathSep)) + "\n";
+          js = `${js}\n//# sourceMappingURL=${helpers.baseFileName(sourceMapPath, false, useWinPathSep)}\n`;
         }
         fs.writeFile(jsPath, js, function(err) {
           if (err) {
             printLine(err.message);
             return process.exit(1);
           } else if (opts.compile && opts.watch) {
-            return timeLog("compiled " + sourcePath);
+            return timeLog(`compiled ${sourcePath}`);
           }
         });
       }
       if (generatedSourceMap) {
         return fs.writeFile(sourceMapPath, generatedSourceMap, function(err) {
           if (err) {
-            printLine("Could not write source map: " + err.message);
+            printLine(`Could not write source map: ${err.message}`);
             return process.exit(1);
           }
         });
@@ -515,7 +515,7 @@
   };
 
   timeLog = function(message) {
-    return console.log(((new Date).toLocaleTimeString()) + " - " + message);
+    return console.log(`${(new Date).toLocaleTimeString()} - ${message}`);
   };
 
   printTokens = function(tokens) {
@@ -527,7 +527,7 @@
         token = tokens[i];
         tag = token[0];
         value = token[1].toString().replace(/\n/, '\\n');
-        results.push("[" + tag + " " + value + "]");
+        results.push(`[${tag} ${value}]`);
       }
       return results;
     })();
@@ -595,7 +595,7 @@
   };
 
   version = function() {
-    return printLine("CoffeeScript version " + CoffeeScript.VERSION);
+    return printLine(`CoffeeScript version ${CoffeeScript.VERSION}`);
   };
 
 }).call(this);
diff --git a/lib/coffee-script/grammar.js b/lib/coffee-script/grammar.js
index 3df53f35ea..bd6dbe98ac 100644
--- a/lib/coffee-script/grammar.js
+++ b/lib/coffee-script/grammar.js
@@ -13,19 +13,19 @@
     if (!action) {
       return [patternString, '$$ = $1;', options];
     }
-    action = (match = unwrap.exec(action)) ? match[1] : "(" + action + "())";
+    action = (match = unwrap.exec(action)) ? match[1] : `(${action}())`;
     action = action.replace(/\bnew /g, '$&yy.');
     action = action.replace(/\b(?:Block\.wrap|extend)\b/g, 'yy.$&');
     addLocationDataFn = function(first, last) {
       if (!last) {
-        return "yy.addLocationDataFn(@" + first + ")";
+        return `yy.addLocationDataFn(@${first})`;
       } else {
-        return "yy.addLocationDataFn(@" + first + ", @" + last + ")";
+        return `yy.addLocationDataFn(@${first}, @${last})`;
       }
     };
     action = action.replace(/LOC\(([0-9]*)\)/g, addLocationDataFn('$1'));
     action = action.replace(/LOC\(([0-9]*),\s*([0-9]*)\)/g, addLocationDataFn('$1', '$2'));
-    return [patternString, "$$ = " + (addLocationDataFn(1, patternCount)) + "(" + action + ");", options];
+    return [patternString, `$$ = ${addLocationDataFn(1, patternCount)}(${action});`, options];
   };
 
   grammar = {
@@ -798,7 +798,7 @@
           }
         }
         if (name === 'Root') {
-          alt[1] = "return " + alt[1];
+          alt[1] = `return ${alt[1]}`;
         }
         results.push(alt);
       }
diff --git a/lib/coffee-script/helpers.js b/lib/coffee-script/helpers.js
index 4b8f210f41..2c2a440029 100644
--- a/lib/coffee-script/helpers.js
+++ b/lib/coffee-script/helpers.js
@@ -100,7 +100,7 @@
   exports.invertLiterate = function(code) {
     var generateRandomToken, i, item, len1, out, ref1, token;
     generateRandomToken = function() {
-      return "" + (Math.random() * Date.now());
+      return `${Math.random() * Date.now()}`;
     };
     while (token === void 0 || code.indexOf(token) !== -1) {
       token = generateRandomToken();
@@ -111,7 +111,7 @@
     for (i = 0, len1 = ref1.length; i < len1; i++) {
       item = ref1[i];
       if (item.type === 'code') {
-        out += item.text + "\n";
+        out += `${item.text}\n`;
       }
     }
     out.replace(token, "\t");
@@ -148,7 +148,7 @@
       locationData = obj;
     }
     if (locationData) {
-      return ((locationData.first_line + 1) + ":" + (locationData.first_column + 1) + "-") + ((locationData.last_line + 1) + ":" + (locationData.last_column + 1));
+      return `${locationData.first_line + 1}:${locationData.first_column + 1}-` + `${locationData.last_line + 1}:${locationData.last_column + 1}`;
     } else {
       return "No location data";
     }
@@ -218,12 +218,12 @@
     }
     if ((ref4 = this.colorful) != null ? ref4 : colorsEnabled) {
       colorize = function(str) {
-        return "\x1B[1;31m" + str + "\x1B[0m";
+        return `\x1B[1;31m${str}\x1B[0m`;
       };
       codeLine = codeLine.slice(0, start) + colorize(codeLine.slice(start, end)) + codeLine.slice(end);
       marker = colorize(marker);
     }
-    return filename + ":" + (first_line + 1) + ":" + (first_column + 1) + ": error: " + this.message + "\n" + codeLine + "\n" + marker;
+    return `${filename}:${first_line + 1}:${first_column + 1}: error: ${this.message}\n${codeLine}\n${marker}`;
   };
 
   exports.nameWhitespaceCharacter = function(string) {
diff --git a/lib/coffee-script/lexer.js b/lib/coffee-script/lexer.js
index ffca2fdf32..396a9d2e75 100644
--- a/lib/coffee-script/lexer.js
+++ b/lib/coffee-script/lexer.js
@@ -42,7 +42,7 @@
       }
       this.closeIndentation();
       if (end = this.ends.pop()) {
-        this.error("missing " + end.tag, end.origin[2]);
+        this.error(`missing ${end.tag}`, end.origin[2]);
       }
       if (opts.rewrite === false) {
         return this.tokens;
@@ -56,7 +56,7 @@
       }
       code = code.replace(/\r/g, '').replace(TRAILING_SPACES, '');
       if (WHITESPACE.test(code)) {
-        code = "\n" + code;
+        code = `\n${code}`;
         this.chunkLine--;
       }
       if (this.literate) {
@@ -133,7 +133,7 @@
         this.seenFor = false;
       }
       if (tag === 'IDENTIFIER' && indexOf.call(RESERVED, id) >= 0) {
-        this.error("reserved word '" + id + "'", {
+        this.error(`reserved word '${id}'`, {
           length: id.length
         });
       }
@@ -187,22 +187,22 @@
       lexedLength = number.length;
       switch (false) {
         case !/^0[BOX]/.test(number):
-          this.error("radix prefix in '" + number + "' must be lowercase", {
+          this.error(`radix prefix in '${number}' must be lowercase`, {
             offset: 1
           });
           break;
         case !/^(?!0x).*E/.test(number):
-          this.error("exponential notation in '" + number + "' must be indicated with a lowercase 'e'", {
+          this.error(`exponential notation in '${number}' must be indicated with a lowercase 'e'`, {
             offset: number.indexOf('E')
           });
           break;
         case !/^0\d*[89]/.test(number):
-          this.error("decimal literal '" + number + "' must not be prefixed with '0'", {
+          this.error(`decimal literal '${number}' must not be prefixed with '0'`, {
             length: lexedLength
           });
           break;
         case !/^0\d+/.test(number):
-          this.error("octal literal '" + number + "' must be prefixed with '0o'", {
+          this.error(`octal literal '${number}' must be prefixed with '0o'`, {
             length: lexedLength
           });
       }
@@ -269,7 +269,7 @@
           }
         }
         if (indent) {
-          indentRegex = RegExp("\\n" + indent, "g");
+          indentRegex = RegExp(`\\n${indent}`, "g");
         }
         this.mergeInterpolationTokens(tokens, {
           delimiter: delimiter
@@ -312,13 +312,13 @@
       comment = match[0], here = match[1];
       if (here) {
         if (match = HERECOMMENT_ILLEGAL.exec(comment)) {
-          this.error("block comments cannot contain " + match[0], {
+          this.error(`block comments cannot contain ${match[0]}`, {
             offset: match.index,
             length: match[0].length
           });
         }
         if (here.indexOf('\n') >= 0) {
-          here = here.replace(RegExp("\\n" + (repeat(' ', this.indent)), "g"), '\n');
+          here = here.replace(RegExp(`\\n${repeat(' ', this.indent)}`, "g"), '\n');
         }
         this.token('HERECOMMENT', here, 0, comment.length);
       }
@@ -341,7 +341,7 @@
       var body, closed, end, flags, index, match, origin, prev, ref2, ref3, ref4, regex, tokens;
       switch (false) {
         case !(match = REGEX_ILLEGAL.exec(this.chunk)):
-          this.error("regular expressions cannot begin with " + match[2], {
+          this.error(`regular expressions cannot begin with ${match[2]}`, {
             offset: match.index + match[1].length
           });
           break;
@@ -377,7 +377,7 @@
       origin = this.makeToken('REGEX', null, 0, end);
       switch (false) {
         case !!VALID_FLAGS.test(flags):
-          this.error("invalid regular expression flags " + flags, {
+          this.error(`invalid regular expression flags ${flags}`, {
             offset: index,
             length: flags.length
           });
@@ -386,9 +386,9 @@
           if (body == null) {
             body = this.formatHeregex(tokens[0][1]);
           }
-          this.token('REGEX', "" + (this.makeDelimitedLiteral(body, {
+          this.token('REGEX', `${this.makeDelimitedLiteral(body, {
             delimiter: '/'
-          })) + flags, 0, end, origin);
+          })}${flags}`, 0, end, origin);
           break;
         default:
           this.token('REGEX_START', '(', 0, 0, origin);
@@ -702,7 +702,7 @@
         offsetInChunk += index;
       }
       if (str.slice(0, delimiter.length) !== delimiter) {
-        this.error("missing " + delimiter, {
+        this.error(`missing ${delimiter}`, {
           length: delimiter.length
         });
       }
@@ -793,7 +793,7 @@
       ref2 = this.ends, prev = ref2[ref2.length - 1];
       if (tag !== (wanted = prev != null ? prev.tag : void 0)) {
         if ('OUTDENT' !== wanted) {
-          this.error("unmatched " + tag);
+          this.error(`unmatched ${tag}`);
         }
         ref3 = this.indents, lastIndent = ref3[ref3.length - 1];
         this.outdentToken(lastIndent, true);
@@ -879,8 +879,8 @@
         return;
       }
       message = octal ? "octal escape sequences are not allowed" : "invalid escape sequence";
-      invalidEscape = "\\" + (octal || hex || unicode);
-      return this.error(message + " " + invalidEscape, {
+      invalidEscape = `\\${octal || hex || unicode}`;
+      return this.error(`${message} ${invalidEscape}`, {
         offset: ((ref2 = options.offsetInChunk) != null ? ref2 : 0) + match.index + before.length,
         length: invalidEscape.length
       });
@@ -891,7 +891,7 @@
       if (body === '' && options.delimiter === '/') {
         body = '(?:)';
       }
-      regex = RegExp("(\\\\\\\\)|(\\\\0(?=[1-7]))|\\\\?(" + options.delimiter + ")|\\\\?(?:(\\n)|(\\r)|(\\u2028)|(\\u2029))|(\\\\.)", "g");
+      regex = RegExp(`(\\\\\\\\)|(\\\\0(?=[1-7]))|\\\\?(${options.delimiter})|\\\\?(?:(\\n)|(\\r)|(\\u2028)|(\\u2029))|(\\\\.)`, "g");
       body = body.replace(regex, function(match, backslash, nul, delimiter, lf, cr, ls, ps, other) {
         switch (false) {
           case !backslash:
@@ -903,7 +903,7 @@
           case !nul:
             return '\\x00';
           case !delimiter:
-            return "\\" + delimiter;
+            return `\\${delimiter}`;
           case !lf:
             return '\\n';
           case !cr:
@@ -914,13 +914,13 @@
             return '\\u2029';
           case !other:
             if (options.double) {
-              return "\\" + other;
+              return `\\${other}`;
             } else {
               return other;
             }
         }
       });
-      return "" + options.delimiter + body + options.delimiter;
+      return `${options.delimiter}${body}${options.delimiter}`;
     };
 
     Lexer.prototype.error = function(message, options = {}) {
@@ -940,11 +940,11 @@
   isUnassignable = function(name, displayName = name) {
     switch (false) {
       case indexOf.call([...JS_KEYWORDS, ...COFFEE_KEYWORDS], name) < 0:
-        return "keyword '" + displayName + "' can't be assigned";
+        return `keyword '${displayName}' can't be assigned`;
       case indexOf.call(STRICT_PROSCRIBED, name) < 0:
-        return "'" + displayName + "' can't be assigned";
+        return `'${displayName}' can't be assigned`;
       case indexOf.call(RESERVED, name) < 0:
-        return "reserved word '" + displayName + "' can't be assigned";
+        return `reserved word '${displayName}' can't be assigned`;
       default:
         return false;
     }
diff --git a/lib/coffee-script/nodes.js b/lib/coffee-script/nodes.js
index f0550b3d79..b48924d7e3 100644
--- a/lib/coffee-script/nodes.js
+++ b/lib/coffee-script/nodes.js
@@ -38,13 +38,13 @@
   exports.CodeFragment = CodeFragment = (function() {
     function CodeFragment(parent, code) {
       var ref3;
-      this.code = "" + code;
+      this.code = `${code}`;
       this.locationData = parent != null ? parent.locationData : void 0;
       this.type = (parent != null ? (ref3 = parent.constructor) != null ? ref3.name : void 0 : void 0) || 'unknown';
     }
 
     CodeFragment.prototype.toString = function() {
-      return "" + this.code + (this.locationData ? ": " + locationDataToString(this.locationData) : '');
+      return `${this.code}${(this.locationData ? ": " + locationDataToString(this.locationData) : '')}`;
     };
 
     return CodeFragment;
@@ -142,7 +142,7 @@
       var me;
       me = this.unwrapAll();
       if (res) {
-        return new Call(new Literal(res + ".push"), [me]);
+        return new Call(new Literal(`${res}.push`), [me]);
       } else {
         return new Return(me);
       }
@@ -384,7 +384,7 @@
           node.front = true;
           fragments = node.compileToFragments(o);
           if (!node.isStatement(o)) {
-            fragments.unshift(this.makeCode("" + this.tab));
+            fragments.unshift(this.makeCode(`${this.tab}`));
             fragments.push(this.makeCode(";"));
           }
           compiledNodes.push(fragments);
@@ -484,17 +484,17 @@
           if (i) {
             fragments.push(this.makeCode('\n'));
           }
-          fragments.push(this.makeCode(this.tab + "var "));
+          fragments.push(this.makeCode(`${this.tab}var `));
           if (declars) {
             fragments.push(this.makeCode(scope.declaredVariables().join(', ')));
           }
           if (assigns) {
             if (declars) {
-              fragments.push(this.makeCode(",\n" + (this.tab + TAB)));
+              fragments.push(this.makeCode(`,\n${this.tab + TAB}`));
             }
-            fragments.push(this.makeCode(scope.assignedVariables().join(",\n" + (this.tab + TAB))));
+            fragments.push(this.makeCode(scope.assignedVariables().join(`,\n${this.tab + TAB}`)));
           }
-          fragments.push(this.makeCode(";\n" + (this.spaced ? '\n' : '')));
+          fragments.push(this.makeCode(`;\n${(this.spaced ? '\n' : '')}`));
         } else if (fragments.length && post.length) {
           fragments.push(this.makeCode("\n"));
         }
@@ -531,7 +531,7 @@
     };
 
     Literal.prototype.toString = function() {
-      return " " + (this.isStatement() ? Literal.__super__.toString.call(this, ...arguments) : this.constructor.name) + ": " + this.value;
+      return ` ${(this.isStatement() ? Literal.__super__.toString.call(this, ...arguments) : this.constructor.name)}: ${this.value}`;
     };
 
     return Literal;
@@ -665,7 +665,7 @@
     };
 
     StatementLiteral.prototype.compileNode = function(o) {
-      return [this.makeCode("" + this.tab + this.value + ";")];
+      return [this.makeCode(`${this.tab}${this.value};`)];
     };
 
     return StatementLiteral;
@@ -754,7 +754,7 @@
     Return.prototype.compileNode = function(o) {
       var answer;
       answer = [];
-      answer.push(this.makeCode(this.tab + ("return" + (this.expression ? " " : ""))));
+      answer.push(this.makeCode(this.tab + `return${(this.expression ? " " : "")}`));
       if (this.expression) {
         answer = answer.concat(this.expression.compileToFragments(o, LEVEL_PAREN));
       }
@@ -1010,7 +1010,7 @@
     Comment.prototype.compileNode = function(o, level) {
       var code, comment;
       comment = this.comment.replace(/^(\s*)#(?=\s)/gm, "$1 *");
-      code = "/*" + (multident(comment, this.tab)) + (indexOf.call(comment, '\n') >= 0 ? "\n" + this.tab : '') + " */";
+      code = `/*${multident(comment, this.tab)}${(indexOf.call(comment, '\n') >= 0 ? `\n${this.tab}` : '')} */`;
       if ((level || o.level) === LEVEL_TOP) {
         code = o.indent + code;
       }
@@ -1062,7 +1062,7 @@
         }
         rite = new Call(rite, this.args);
         rite.isNew = this.isNew;
-        left = new Literal("typeof " + (left.compile(o)) + " === \"function\"");
+        left = new Literal(`typeof ${left.compile(o)} === \"function\"`);
         return new If(left, new Value(rite), {
           soak: true
         });
@@ -1114,7 +1114,7 @@
       }
       fragments = [];
       if (this instanceof SuperCall) {
-        preface = this.superReference(o) + (".call(" + (this.superThis(o)));
+        preface = this.superReference(o) + `.call(${this.superThis(o)}`;
         if (compiledArgs.length) {
           preface += ", ";
         }
@@ -1167,7 +1167,7 @@
         accesses.push(nref != null ? new Index(nref) : name);
         return (new Value(bref != null ? bref : klass, accesses)).compile(o);
       } else if (method != null ? method.ctor : void 0) {
-        return method.name + ".__super__.constructor";
+        return `${method.name}.__super__.constructor`;
       } else {
         return this.error('cannot call super outside of an instance method.');
       }
@@ -1205,7 +1205,6 @@
     }
 
     TaggedTemplateCall.prototype.compileNode = function(o) {
-      o.inTaggedTemplateCall = true;
       return this.variable.compileToFragments(o, LEVEL_ACCESS).concat(this.args[0].compileToFragments(o, LEVEL_LIST));
     };
 
@@ -1323,23 +1322,23 @@
       idx = del(o, 'index');
       idxName = del(o, 'name');
       namedIndex = idxName && idxName !== idx;
-      varPart = idx + " = " + this.fromC;
+      varPart = `${idx} = ${this.fromC}`;
       if (this.toC !== this.toVar) {
-        varPart += ", " + this.toC;
+        varPart += `, ${this.toC}`;
       }
       if (this.step !== this.stepVar) {
-        varPart += ", " + this.step;
+        varPart += `, ${this.step}`;
       }
-      ref3 = [idx + " <" + this.equals, idx + " >" + this.equals], lt = ref3[0], gt = ref3[1];
-      condPart = this.stepNum != null ? this.stepNum > 0 ? lt + " " + this.toVar : gt + " " + this.toVar : known ? ((ref4 = [this.fromNum, this.toNum], from = ref4[0], to = ref4[1], ref4), from <= to ? lt + " " + to : gt + " " + to) : (cond = this.stepVar ? this.stepVar + " > 0" : this.fromVar + " <= " + this.toVar, cond + " ? " + lt + " " + this.toVar + " : " + gt + " " + this.toVar);
-      stepPart = this.stepVar ? idx + " += " + this.stepVar : known ? namedIndex ? from <= to ? "++" + idx : "--" + idx : from <= to ? idx + "++" : idx + "--" : namedIndex ? cond + " ? ++" + idx + " : --" + idx : cond + " ? " + idx + "++ : " + idx + "--";
+      ref3 = [`${idx} <${this.equals}`, `${idx} >${this.equals}`], lt = ref3[0], gt = ref3[1];
+      condPart = this.stepNum != null ? this.stepNum > 0 ? `${lt} ${this.toVar}` : `${gt} ${this.toVar}` : known ? ((ref4 = [this.fromNum, this.toNum], from = ref4[0], to = ref4[1], ref4), from <= to ? `${lt} ${to}` : `${gt} ${to}`) : (cond = this.stepVar ? `${this.stepVar} > 0` : `${this.fromVar} <= ${this.toVar}`, `${cond} ? ${lt} ${this.toVar} : ${gt} ${this.toVar}`);
+      stepPart = this.stepVar ? `${idx} += ${this.stepVar}` : known ? namedIndex ? from <= to ? `++${idx}` : `--${idx}` : from <= to ? `${idx}++` : `${idx}--` : namedIndex ? `${cond} ? ++${idx} : --${idx}` : `${cond} ? ${idx}++ : ${idx}--`;
       if (namedIndex) {
-        varPart = idxName + " = " + varPart;
+        varPart = `${idxName} = ${varPart}`;
       }
       if (namedIndex) {
-        stepPart = idxName + " = " + stepPart;
+        stepPart = `${idxName} = ${stepPart}`;
       }
-      return [this.makeCode(varPart + "; " + condPart + "; " + stepPart)];
+      return [this.makeCode(`${varPart}; ${condPart}; ${stepPart}`)];
     };
 
     Range.prototype.compileArray = function(o) {
@@ -1354,30 +1353,30 @@
         if (this.exclusive) {
           range.pop();
         }
-        return [this.makeCode("[" + (range.join(', ')) + "]")];
+        return [this.makeCode(`[${range.join(', ')}]`)];
       }
       idt = this.tab + TAB;
       i = o.scope.freeVariable('i', {
         single: true
       });
       result = o.scope.freeVariable('results');
-      pre = "\n" + idt + result + " = [];";
+      pre = `\n${idt}${result} = [];`;
       if (known) {
         o.index = i;
         body = fragmentsToText(this.compileNode(o));
       } else {
-        vars = (i + " = " + this.fromC) + (this.toC !== this.toVar ? ", " + this.toC : '');
-        cond = this.fromVar + " <= " + this.toVar;
-        body = "var " + vars + "; " + cond + " ? " + i + " <" + this.equals + " " + this.toVar + " : " + i + " >" + this.equals + " " + this.toVar + "; " + cond + " ? " + i + "++ : " + i + "--";
+        vars = `${i} = ${this.fromC}` + (this.toC !== this.toVar ? `, ${this.toC}` : '');
+        cond = `${this.fromVar} <= ${this.toVar}`;
+        body = `var ${vars}; ${cond} ? ${i} <${this.equals} ${this.toVar} : ${i} >${this.equals} ${this.toVar}; ${cond} ? ${i}++ : ${i}--`;
       }
-      post = "{ " + result + ".push(" + i + "); }\n" + idt + "return " + result + ";\n" + o.indent;
+      post = `{ ${result}.push(${i}); }\n${idt}return ${result};\n${o.indent}`;
       hasArgs = function(node) {
         return node != null ? node.contains(isLiteralArguments) : void 0;
       };
       if (hasArgs(this.from) || hasArgs(this.to)) {
         args = ', arguments';
       }
-      return [this.makeCode("(function() {" + pre + "\n" + idt + "for (" + body + ")" + post + "}).apply(this" + (args != null ? args : '') + ")")];
+      return [this.makeCode(`(function() {${pre}\n${idt}for (${body})${post}}).apply(this${args != null ? args : ''})`)];
     };
 
     return Range;
@@ -1402,10 +1401,10 @@
         compiled = to.compileToFragments(o, LEVEL_PAREN);
         compiledText = fragmentsToText(compiled);
         if (!(!this.range.exclusive && +compiledText === -1)) {
-          toStr = ', ' + (this.range.exclusive ? compiledText : to.isNumber() ? "" + (+compiledText + 1) : (compiled = to.compileToFragments(o, LEVEL_ACCESS), "+" + (fragmentsToText(compiled)) + " + 1 || 9e9"));
+          toStr = ', ' + (this.range.exclusive ? compiledText : to.isNumber() ? `${+compiledText + 1}` : (compiled = to.compileToFragments(o, LEVEL_ACCESS), `+${fragmentsToText(compiled)} + 1 || 9e9`));
         }
       }
-      return [this.makeCode(".slice(" + (fragmentsToText(fromCompiled)) + (toStr || '') + ")")];
+      return [this.makeCode(`.slice(${fragmentsToText(fromCompiled)}${toStr || ''})`)];
     };
 
     return Slice;
@@ -1437,14 +1436,14 @@
       idt = o.indent += TAB;
       lastNoncom = this.lastNonComment(this.properties);
       answer = [];
-      answer.push(this.makeCode("{" + (props.length === 0 ? '}' : '\n')));
+      answer.push(this.makeCode(`{${(props.length === 0 ? '}' : '\n')}`));
       for (i = k = 0, len2 = props.length; k < len2; i = ++k) {
         prop = props[i];
         join = i === props.length - 1 ? '' : prop === lastNoncom || prop instanceof Comment ? '\n' : ',\n';
         indent = prop instanceof Comment ? '' : idt;
         if (prop instanceof Assign) {
           if (prop.context !== 'object') {
-            prop.operatorToken.error("unexpected " + prop.operatorToken.value);
+            prop.operatorToken.error(`unexpected ${prop.operatorToken.value}`);
           }
           if (prop.variable instanceof Value && prop.variable.hasProperties()) {
             prop.variable.error('invalid object key');
@@ -1473,7 +1472,7 @@
         }
       }
       if (props.length !== 0) {
-        answer.push(this.makeCode("\n" + this.tab + "}"));
+        answer.push(this.makeCode(`\n${this.tab}}`));
       }
       if (this.front) {
         return this.wrapInBraces(answer);
@@ -1532,8 +1531,8 @@
         answer.push(...fragments);
       }
       if (fragmentsToText(answer).indexOf('\n') >= 0) {
-        answer.unshift(this.makeCode("[\n" + o.indent));
-        answer.push(this.makeCode("\n" + this.tab + "]"));
+        answer.unshift(this.makeCode(`[\n${o.indent}`));
+        answer.push(this.makeCode(`\n${this.tab}]`));
       } else {
         answer.unshift(this.makeCode("["));
         answer.push(this.makeCode("]"));
@@ -1591,7 +1590,7 @@
         }
       }
       if (indexOf.call(JS_FORBIDDEN, name) >= 0) {
-        return "_" + name;
+        return `_${name}`;
       } else {
         return name;
       }
@@ -1618,7 +1617,7 @@
       for (j = 0, len1 = ref3.length; j < len1; j++) {
         bvar = ref3[j];
         lhs = (new Value(new ThisLiteral, [new Access(bvar)])).compile(o);
-        this.ctor.body.unshift(new Literal(lhs + " = " + (utility('bind', o)) + "(" + lhs + ", this)"));
+        this.ctor.body.unshift(new Literal(`${lhs} = ${utility('bind', o)}(${lhs}, this)`));
       }
     };
 
@@ -1704,9 +1703,9 @@
       if (!this.ctor) {
         this.ctor = new Code;
         if (this.externalCtor) {
-          this.ctor.body.push(new Literal(this.externalCtor + ".apply(this, arguments)"));
+          this.ctor.body.push(new Literal(`${this.externalCtor}.apply(this, arguments)`));
         } else if (this.parent) {
-          this.ctor.body.push(new Literal(name + ".__super__.constructor.apply(this, arguments)"));
+          this.ctor.body.push(new Literal(`${name}.__super__.constructor.apply(this, arguments)`));
         }
         this.ctor.body.makeReturn();
         this.body.expressions.unshift(this.ctor);
@@ -1783,7 +1782,7 @@
 
     ModuleDeclaration.prototype.checkScope = function(o, moduleDeclarationType) {
       if (o.indent.length !== 0) {
-        return this.error(moduleDeclarationType + " statements must be at top-level scope");
+        return this.error(`${moduleDeclarationType} statements must be at top-level scope`);
       }
     };
 
@@ -1803,7 +1802,7 @@
       this.checkScope(o, 'import');
       o.importedSymbols = [];
       code = [];
-      code.push(this.makeCode(this.tab + "import "));
+      code.push(this.makeCode(`${this.tab}import `));
       if (this.clause != null) {
         code.push(...this.clause.compileNode(o));
       }
@@ -1861,7 +1860,7 @@
       var code, ref3;
       this.checkScope(o, 'export');
       code = [];
-      code.push(this.makeCode(this.tab + "export "));
+      code.push(this.makeCode(`${this.tab}export `));
       if (this instanceof ExportDefaultDeclaration) {
         code.push(this.makeCode('default '));
       }
@@ -1878,7 +1877,7 @@
         code = code.concat(this.clause.compileNode(o));
       }
       if (((ref3 = this.source) != null ? ref3.value : void 0) != null) {
-        code.push(this.makeCode(" from " + this.source.value));
+        code.push(this.makeCode(` from ${this.source.value}`));
       }
       code.push(this.makeCode(';'));
       return code;
@@ -1945,11 +1944,11 @@
         return results;
       }).call(this);
       if (this.specifiers.length !== 0) {
-        code.push(this.makeCode("{\n" + o.indent));
+        code.push(this.makeCode(`{\n${o.indent}`));
         for (index = j = 0, len1 = compiledList.length; j < len1; index = ++j) {
           fragments = compiledList[index];
           if (index) {
-            code.push(this.makeCode(",\n" + o.indent));
+            code.push(this.makeCode(`,\n${o.indent}`));
           }
           code.push(...fragments);
         }
@@ -2004,7 +2003,7 @@
       code = [];
       code.push(this.makeCode(this.original.value));
       if (this.alias != null) {
-        code.push(this.makeCode(" as " + this.alias.value));
+        code.push(this.makeCode(` as ${this.alias.value}`));
       }
       return code;
     };
@@ -2023,7 +2022,7 @@
     ImportSpecifier.prototype.compileNode = function(o) {
       var ref3;
       if ((ref3 = this.identifier, indexOf.call(o.importedSymbols, ref3) >= 0) || o.scope.check(this.identifier)) {
-        this.error("'" + this.identifier + "' has already been declared");
+        this.error(`'${this.identifier}' has already been declared`);
       } else {
         o.importedSymbols.push(this.identifier);
       }
@@ -2085,7 +2084,7 @@
 
     Assign.prototype.checkAssignability = function(o, varBase) {
       if (Object.prototype.hasOwnProperty.call(o.scope.positions, varBase.value) && o.scope.variables[o.scope.positions[varBase.value]].type === 'import') {
-        return varBase.error("'" + varBase.value + "' is read-only");
+        return varBase.error(`'${varBase.value}' is read-only`);
       }
     };
 
@@ -2130,7 +2129,7 @@
       if (!this.context) {
         varBase = this.variable.unwrapAll();
         if (!varBase.isAssignable()) {
-          this.variable.error("'" + (this.variable.compile(o)) + "' can't be assigned");
+          this.variable.error(`'${this.variable.compile(o)}' can't be assigned`);
         }
         if (!(typeof varBase.hasProperties === "function" ? varBase.hasProperties() : void 0)) {
           if (this.moduleDeclaration) {
@@ -2159,7 +2158,7 @@
         }
         return compiledName.concat(this.makeCode(": "), val);
       }
-      answer = compiledName.concat(this.makeCode(" " + (this.context || '=') + " "), val);
+      answer = compiledName.concat(this.makeCode(` ${this.context || '='} `), val);
       if (o.level <= LEVEL_LIST) {
         return answer;
       } else {
@@ -2219,7 +2218,7 @@
       assigns = [];
       expandedIdx = false;
       if (!(value.unwrap() instanceof IdentifierLiteral) || this.variable.assigns(vvarText)) {
-        assigns.push([this.makeCode((ref = o.scope.freeVariable('ref')) + " = "), ...vvar]);
+        assigns.push([this.makeCode(`${(ref = o.scope.freeVariable('ref'))} = `), ...vvar]);
         vvar = [this.makeCode(ref)];
         vvarText = ref;
       }
@@ -2229,27 +2228,27 @@
         if (!expandedIdx && obj instanceof Splat) {
           name = obj.name.unwrap().value;
           obj = obj.unwrap();
-          val = olen + " <= " + vvarText + ".length ? " + (utility('slice', o)) + ".call(" + vvarText + ", " + i;
+          val = `${olen} <= ${vvarText}.length ? ${utility('slice', o)}.call(${vvarText}, ${i}`;
           if (rest = olen - i - 1) {
             ivar = o.scope.freeVariable('i', {
               single: true
             });
-            val += ", " + ivar + " = " + vvarText + ".length - " + rest + ") : (" + ivar + " = " + i + ", [])";
+            val += `, ${ivar} = ${vvarText}.length - ${rest}) : (${ivar} = ${i}, [])`;
           } else {
             val += ") : []";
           }
           val = new Literal(val);
-          expandedIdx = ivar + "++";
+          expandedIdx = `${ivar}++`;
         } else if (!expandedIdx && obj instanceof Expansion) {
           if (rest = olen - i - 1) {
             if (rest === 1) {
-              expandedIdx = vvarText + ".length - 1";
+              expandedIdx = `${vvarText}.length - 1`;
             } else {
               ivar = o.scope.freeVariable('i', {
                 single: true
               });
-              val = new Literal(ivar + " = " + vvarText + ".length - " + rest);
-              expandedIdx = ivar + "++";
+              val = new Literal(`${ivar} = ${vvarText}.length - ${rest}`);
+              expandedIdx = `${ivar}++`;
               assigns.push(val.compileToFragments(o, LEVEL_LIST));
             }
           }
@@ -2305,7 +2304,7 @@
       var fragments, left, ref3, right;
       ref3 = this.variable.cacheReference(o), left = ref3[0], right = ref3[1];
       if (!left.properties.length && left.base instanceof Literal && !(left.base instanceof ThisLiteral) && !o.scope.check(left.base.value)) {
-        this.variable.error("the variable \"" + left.base.value + "\" can't be assigned with " + this.context + " because it has not been declared before");
+        this.variable.error(`the variable \"${left.base.value}\" can't be assigned with ${this.context} because it has not been declared before`);
       }
       if (indexOf.call(this.context, "?") >= 0) {
         o.isExistentialEquals = true;
@@ -2353,7 +2352,7 @@
         to = "9e9";
       }
       ref5 = this.value.cache(o, LEVEL_LIST), valDef = ref5[0], valRef = ref5[1];
-      answer = [].concat(this.makeCode("[].splice.apply(" + name + ", [" + fromDecl + ", " + to + "].concat("), valDef, this.makeCode(")), "), valRef);
+      answer = [].concat(this.makeCode(`[].splice.apply(${name}, [${fromDecl}, ${to}].concat(`), valDef, this.makeCode(")), "), valRef);
       if (o.level > LEVEL_TOP) {
         return this.wrapInBraces(answer);
       } else {
@@ -2421,7 +2420,7 @@
       paramNames = [];
       this.eachParamName((name, node) => {
         if (indexOf.call(paramNames, name) >= 0) {
-          node.error("multiple parameters named '" + name + "'");
+          node.error(`multiple parameters named '${name}'`);
         }
         return paramNames.push(name);
       });
@@ -2524,7 +2523,7 @@
       }
       answer.push(this.makeCode(!this.bound ? ') {' : ') => {'));
       if (!this.body.isEmpty()) {
-        answer = answer.concat(this.makeCode("\n"), this.body.compileWithDeclarations(o), this.makeCode("\n" + this.tab));
+        answer = answer.concat(this.makeCode("\n"), this.body.compileWithDeclarations(o), this.makeCode(`\n${this.tab}`));
       }
       answer.push(this.makeCode('}'));
       if (this.ctor) {
@@ -2572,7 +2571,7 @@
       }
       if (this.name instanceof Obj && this.name.generated) {
         token = this.name.objects[0].operatorToken;
-        token.error("unexpected " + token.value);
+        token.error(`unexpected ${token.value}`);
       }
     }
 
@@ -2591,7 +2590,7 @@
       if (node["this"]) {
         name = node.properties[0].name.value;
         if (indexOf.call(JS_FORBIDDEN, name) >= 0) {
-          name = "_" + name;
+          name = `_${name}`;
         }
         node = new IdentifierLiteral(o.scope.freeVariable(name));
       } else if (node.isComplex()) {
@@ -2609,7 +2608,7 @@
     Param.prototype.eachName = function(iterator, name = this.name) {
       var atParam, j, len1, node, obj, ref3, ref4;
       atParam = function(obj) {
-        return iterator("@" + obj.properties[0].name.value, obj);
+        return iterator(`@${obj.properties[0].name.value}`, obj);
       };
       if (name instanceof Literal) {
         return iterator(name.value, name);
@@ -2640,7 +2639,7 @@
             iterator(obj.base.value, obj.base);
           }
         } else if (!(obj instanceof Expansion)) {
-          obj.error("illegal parameter " + (obj.compile()));
+          obj.error(`illegal parameter ${obj.compile()}`);
         }
       }
     };
@@ -2754,7 +2753,7 @@
       } else {
         if (this.returns) {
           body.makeReturn(rvar = o.scope.freeVariable('results'));
-          set = "" + this.tab + rvar + " = [];\n";
+          set = `${this.tab}${rvar} = [];\n`;
         }
         if (this.guard) {
           if (body.expressions.length > 1) {
@@ -2765,11 +2764,11 @@
             }
           }
         }
-        body = [].concat(this.makeCode("\n"), body.compileToFragments(o, LEVEL_TOP), this.makeCode("\n" + this.tab));
+        body = [].concat(this.makeCode("\n"), body.compileToFragments(o, LEVEL_TOP), this.makeCode(`\n${this.tab}`));
       }
       answer = [].concat(this.makeCode(set + this.tab + "while ("), this.condition.compileToFragments(o, LEVEL_PAREN), this.makeCode(") {"), body, this.makeCode("}"));
       if (this.returns) {
-        answer.push(this.makeCode("\n" + this.tab + "return " + rvar + ";"));
+        answer.push(this.makeCode(`\n${this.tab}return ${rvar};`));
       }
       return answer;
     };
@@ -2940,7 +2939,7 @@
         default:
           lhs = this.first.compileToFragments(o, LEVEL_OP);
           rhs = this.second.compileToFragments(o, LEVEL_OP);
-          answer = [].concat(lhs, this.makeCode(" " + this.operator + " "), rhs);
+          answer = [].concat(lhs, this.makeCode(` ${this.operator} `), rhs);
           if (o.level <= LEVEL_OP) {
             return answer;
           } else {
@@ -2953,7 +2952,7 @@
       var fragments, fst, ref3, shared;
       ref3 = this.first.second.cache(o), this.first.second = ref3[0], shared = ref3[1];
       fst = this.first.compileToFragments(o, LEVEL_OP);
-      fragments = fst.concat(this.makeCode(" " + (this.invert ? '&&' : '||') + " "), shared.compileToFragments(o), this.makeCode(" " + this.operator + " "), this.second.compileToFragments(o, LEVEL_OP));
+      fragments = fst.concat(this.makeCode(` ${(this.invert ? '&&' : '||')} `), shared.compileToFragments(o), this.makeCode(` ${this.operator} `), this.second.compileToFragments(o, LEVEL_OP));
       return this.wrapInBraces(fragments);
     };
 
@@ -3002,7 +3001,7 @@
       parts = [];
       op = this.operator;
       if (o.scope.parent == null) {
-        this.error(this.operator + " can only occur inside functions");
+        this.error(`${this.operator} can only occur inside functions`);
       }
       if (((ref3 = o.scope.method) != null ? ref3.bound : void 0) && o.scope.method.isGenerator) {
         this.error('yield cannot occur inside bound (fat arrow) functions');
@@ -3163,11 +3162,11 @@
       tryPart = this.attempt.compileToFragments(o, LEVEL_TOP);
       catchPart = this.recovery ? (generatedErrorVariableName = o.scope.freeVariable('error', {
         reserve: false
-      }), placeholder = new IdentifierLiteral(generatedErrorVariableName), this.errorVariable ? (message = isUnassignable(this.errorVariable.unwrapAll().value), message ? this.errorVariable.error(message) : void 0, this.recovery.unshift(new Assign(this.errorVariable, placeholder))) : void 0, [].concat(this.makeCode(" catch ("), placeholder.compileToFragments(o), this.makeCode(") {\n"), this.recovery.compileToFragments(o, LEVEL_TOP), this.makeCode("\n" + this.tab + "}"))) : !(this.ensure || this.recovery) ? (generatedErrorVariableName = o.scope.freeVariable('error', {
+      }), placeholder = new IdentifierLiteral(generatedErrorVariableName), this.errorVariable ? (message = isUnassignable(this.errorVariable.unwrapAll().value), message ? this.errorVariable.error(message) : void 0, this.recovery.unshift(new Assign(this.errorVariable, placeholder))) : void 0, [].concat(this.makeCode(" catch ("), placeholder.compileToFragments(o), this.makeCode(") {\n"), this.recovery.compileToFragments(o, LEVEL_TOP), this.makeCode(`\n${this.tab}}`))) : !(this.ensure || this.recovery) ? (generatedErrorVariableName = o.scope.freeVariable('error', {
         reserve: false
-      }), [this.makeCode(" catch (" + generatedErrorVariableName + ") {}")]) : [];
-      ensurePart = this.ensure ? [].concat(this.makeCode(" finally {\n"), this.ensure.compileToFragments(o, LEVEL_TOP), this.makeCode("\n" + this.tab + "}")) : [];
-      return [].concat(this.makeCode(this.tab + "try {\n"), tryPart, this.makeCode("\n" + this.tab + "}"), catchPart, ensurePart);
+      }), [this.makeCode(` catch (${generatedErrorVariableName}) {}`)]) : [];
+      ensurePart = this.ensure ? [].concat(this.makeCode(" finally {\n"), this.ensure.compileToFragments(o, LEVEL_TOP), this.makeCode(`\n${this.tab}}`)) : [];
+      return [].concat(this.makeCode(`${this.tab}try {\n`), tryPart, this.makeCode(`\n${this.tab}}`), catchPart, ensurePart);
     };
 
     return Try;
@@ -3214,11 +3213,11 @@
       code = this.expression.compile(o, LEVEL_OP);
       if (this.expression.unwrap() instanceof IdentifierLiteral && !o.scope.check(code)) {
         ref3 = this.negated ? ['===', '||'] : ['!==', '&&'], cmp = ref3[0], cnj = ref3[1];
-        code = "typeof " + code + " " + cmp + " \"undefined\" " + cnj + " " + code + " " + cmp + " null";
+        code = `typeof ${code} ${cmp} \"undefined\" ${cnj} ${code} ${cmp} null`;
       } else {
-        code = code + " " + (this.negated ? '==' : '!=') + " null";
+        code = `${code} ${(this.negated ? '==' : '!=')} null`;
       }
-      return [this.makeCode(o.level <= LEVEL_COND ? code : "(" + code + ")")];
+      return [this.makeCode(o.level <= LEVEL_COND ? code : `(${code})`)];
     };
 
     return Existence;
@@ -3265,15 +3264,22 @@
   exports.StringWithInterpolations = StringWithInterpolations = (function(superClass1) {
     extend1(StringWithInterpolations, superClass1);
 
-    function StringWithInterpolations() {
-      return StringWithInterpolations.__super__.constructor.apply(this, arguments);
+    function StringWithInterpolations(body1) {
+      this.body = body1;
     }
 
+    StringWithInterpolations.prototype.children = ['body'];
+
+    StringWithInterpolations.prototype.unwrap = function() {
+      return this;
+    };
+
+    StringWithInterpolations.prototype.isComplex = function() {
+      return this.body.isComplex();
+    };
+
     StringWithInterpolations.prototype.compileNode = function(o) {
       var element, elements, expr, fragments, j, len1;
-      if (!o.inTaggedTemplateCall) {
-        return StringWithInterpolations.__super__.compileNode.call(this, ...arguments);
-      }
       expr = this.body.unwrap();
       elements = [];
       expr.traverseChildren(false, function(node) {
@@ -3304,7 +3310,7 @@
 
     return StringWithInterpolations;
 
-  })(Parens);
+  })(Base);
 
   exports.For = For = (function(superClass1) {
     extend1(For, superClass1);
@@ -3320,7 +3326,7 @@
         this.index.error('cannot use index with for-from');
       }
       if (this.own && !this.object) {
-        source.ownTag.error("cannot use own with for-" + (this.from ? 'from' : 'in'));
+        source.ownTag.error(`cannot use own with for-${(this.from ? 'from' : 'in')}`);
       }
       if (this.object) {
         ref3 = [this.index, this.name], this.name = ref3[0], this.index = ref3[1];
@@ -3375,7 +3381,7 @@
         });
       }
       kvar = ((this.range || this.from) && name) || index || ivar;
-      kvarAssign = kvar !== ivar ? kvar + " = " : "";
+      kvarAssign = kvar !== ivar ? `${kvar} = ` : "";
       if (this.step && !this.range) {
         ref4 = this.cacheToCodeFragments(this.step.cache(o, LEVEL_LIST, isComplexOrAssignable)), step = ref4[0], stepVar = ref4[1];
         if (this.step.isNumber()) {
@@ -3399,24 +3405,24 @@
       } else {
         svar = this.source.compile(o, LEVEL_LIST);
         if ((name || this.own) && !(this.source.unwrap() instanceof IdentifierLiteral)) {
-          defPart += "" + this.tab + (ref = scope.freeVariable('ref')) + " = " + svar + ";\n";
+          defPart += `${this.tab}${(ref = scope.freeVariable('ref'))} = ${svar};\n`;
           svar = ref;
         }
         if (name && !this.pattern && !this.from) {
-          namePart = name + " = " + svar + "[" + kvar + "]";
+          namePart = `${name} = ${svar}[${kvar}]`;
         }
         if (!this.object && !this.from) {
           if (step !== stepVar) {
-            defPart += "" + this.tab + step + ";\n";
+            defPart += `${this.tab}${step};\n`;
           }
           down = stepNum < 0;
           if (!(this.step && (stepNum != null) && down)) {
             lvar = scope.freeVariable('len');
           }
-          declare = "" + kvarAssign + ivar + " = 0, " + lvar + " = " + svar + ".length";
-          declareDown = "" + kvarAssign + ivar + " = " + svar + ".length - 1";
-          compare = ivar + " < " + lvar;
-          compareDown = ivar + " >= 0";
+          declare = `${kvarAssign}${ivar} = 0, ${lvar} = ${svar}.length`;
+          declareDown = `${kvarAssign}${ivar} = ${svar}.length - 1`;
+          compare = `${ivar} < ${lvar}`;
+          compareDown = `${ivar} >= 0`;
           if (this.step) {
             if (stepNum != null) {
               if (down) {
@@ -3424,19 +3430,19 @@
                 declare = declareDown;
               }
             } else {
-              compare = stepVar + " > 0 ? " + compare + " : " + compareDown;
-              declare = "(" + stepVar + " > 0 ? (" + declare + ") : " + declareDown + ")";
+              compare = `${stepVar} > 0 ? ${compare} : ${compareDown}`;
+              declare = `(${stepVar} > 0 ? (${declare}) : ${declareDown})`;
             }
-            increment = ivar + " += " + stepVar;
+            increment = `${ivar} += ${stepVar}`;
           } else {
-            increment = "" + (kvar !== ivar ? "++" + ivar : ivar + "++");
+            increment = `${(kvar !== ivar ? `++${ivar}` : `${ivar}++`)}`;
           }
-          forPartFragments = [this.makeCode(declare + "; " + compare + "; " + kvarAssign + increment)];
+          forPartFragments = [this.makeCode(`${declare}; ${compare}; ${kvarAssign}${increment}`)];
         }
       }
       if (this.returns) {
-        resultPart = "" + this.tab + rvar + " = [];\n";
-        returnResult = "\n" + this.tab + "return " + rvar + ";";
+        resultPart = `${this.tab}${rvar} = [];\n`;
+        returnResult = `\n${this.tab}return ${rvar};`;
         body.makeReturn(rvar);
       }
       if (this.guard) {
@@ -3449,19 +3455,19 @@
         }
       }
       if (this.pattern) {
-        body.expressions.unshift(new Assign(this.name, this.from ? new IdentifierLiteral(kvar) : new Literal(svar + "[" + kvar + "]")));
+        body.expressions.unshift(new Assign(this.name, this.from ? new IdentifierLiteral(kvar) : new Literal(`${svar}[${kvar}]`)));
       }
       defPartFragments = [].concat(this.makeCode(defPart), this.pluckDirectCall(o, body));
       if (namePart) {
-        varPart = "\n" + idt1 + namePart + ";";
+        varPart = `\n${idt1}${namePart};`;
       }
       if (this.object) {
-        forPartFragments = [this.makeCode(kvar + " in " + svar)];
+        forPartFragments = [this.makeCode(`${kvar} in ${svar}`)];
         if (this.own) {
-          guardPart = "\n" + idt1 + "if (!" + (utility('hasProp', o)) + ".call(" + svar + ", " + kvar + ")) continue;";
+          guardPart = `\n${idt1}if (!${utility('hasProp', o)}.call(${svar}, ${kvar})) continue;`;
         }
       } else if (this.from) {
-        forPartFragments = [this.makeCode(kvar + " of " + svar)];
+        forPartFragments = [this.makeCode(`${kvar} of ${svar}`)];
       }
       bodyFragments = body.compileToFragments(merge(o, {
         indent: idt1
@@ -3469,7 +3475,7 @@
       if (bodyFragments && bodyFragments.length > 0) {
         bodyFragments = [].concat(this.makeCode("\n"), bodyFragments, this.makeCode("\n"));
       }
-      return [].concat(defPartFragments, this.makeCode("" + (resultPart || '') + this.tab + "for ("), forPartFragments, this.makeCode(") {" + guardPart + varPart), bodyFragments, this.makeCode(this.tab + "}" + (returnResult || '')));
+      return [].concat(defPartFragments, this.makeCode(`${resultPart || ''}${this.tab}for (`), forPartFragments, this.makeCode(`) {${guardPart}${varPart}`), bodyFragments, this.makeCode(`${this.tab}}${returnResult || ''}`));
     };
 
     For.prototype.pluckDirectCall = function(o, body) {
@@ -3667,7 +3673,7 @@
       body = this.ensureBlock(this.body).compileToFragments(merge(o, {
         indent: indent
       }));
-      ifPart = [].concat(this.makeCode("if ("), cond, this.makeCode(") {\n"), body, this.makeCode("\n" + this.tab + "}"));
+      ifPart = [].concat(this.makeCode("if ("), cond, this.makeCode(") {\n"), body, this.makeCode(`\n${this.tab}}`));
       if (!child) {
         ifPart.unshift(this.makeCode(this.tab));
       }
@@ -3681,7 +3687,7 @@
       } else {
         answer = answer.concat(this.makeCode("{\n"), this.elseBody.compileToFragments(merge(o, {
           indent: indent
-        }), LEVEL_TOP), this.makeCode("\n" + this.tab + "}"));
+        }), LEVEL_TOP), this.makeCode(`\n${this.tab}}`));
       }
       return answer;
     };
@@ -3709,7 +3715,7 @@
 
   UTILITIES = {
     extend: function(o) {
-      return "function(child, parent) { for (var key in parent) { if (" + (utility('hasProp', o)) + ".call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; }";
+      return `function(child, parent) { for (var key in parent) { if (${utility('hasProp', o)}.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; }`;
     },
     bind: function() {
       return 'function(fn, me){ return function(){ return fn.apply(me, arguments); }; }';
diff --git a/lib/coffee-script/optparse.js b/lib/coffee-script/optparse.js
index c8dab1e715..5e1abad3bc 100644
--- a/lib/coffee-script/optparse.js
+++ b/lib/coffee-script/optparse.js
@@ -48,7 +48,7 @@
             }
           }
           if (isOption && !matchedRule) {
-            throw new Error("unrecognized option: " + arg);
+            throw new Error(`unrecognized option: ${arg}`);
           }
         }
         if (seenNonOptionArg || !isOption) {
@@ -62,7 +62,7 @@
       var j, len, letPart, lines, ref, rule, spaces;
       lines = [];
       if (this.banner) {
-        lines.unshift(this.banner + "\n");
+        lines.unshift(`${this.banner}\n`);
       }
       ref = this.rules;
       for (j = 0, len = ref.length; j < len; j++) {
@@ -72,7 +72,7 @@
         letPart = rule.shortFlag ? rule.shortFlag + ', ' : '    ';
         lines.push('  ' + letPart + rule.longFlag + spaces + rule.description);
       }
-      return "\n" + (lines.join('\n')) + "\n";
+      return `\n${lines.join('\n')}\n`;
     };
 
     return OptionParser;
diff --git a/lib/coffee-script/repl.js b/lib/coffee-script/repl.js
index 5398c804dc..dbf8b6ae5d 100644
--- a/lib/coffee-script/repl.js
+++ b/lib/coffee-script/repl.js
@@ -78,7 +78,7 @@
     rli.removeListener('line', nodeLineListener);
     rli.on('line', function(cmd) {
       if (multiline.enabled) {
-        multiline.buffer += cmd + "\n";
+        multiline.buffer += `${cmd}\n`;
         rli.setPrompt(multiline.prompt);
         rli.prompt(true);
       } else {
@@ -139,7 +139,7 @@
     fd = fs.openSync(filename, 'a');
     repl.rli.addListener('line', function(code) {
       if (code && code.length && code !== '.history' && code !== '.exit' && lastLine !== code) {
-        fs.writeSync(fd, code + "\n");
+        fs.writeSync(fd, `${code}\n`);
         return lastLine = code;
       }
     });
@@ -149,7 +149,7 @@
     return repl.commands[getCommandId(repl, 'history')] = {
       help: 'Show command history',
       action: function() {
-        repl.outputStream.write((repl.rli.history.slice(0).reverse().join('\n')) + "\n");
+        repl.outputStream.write(`${repl.rli.history.slice(0).reverse().join('\n')}\n`);
         return repl.displayPrompt();
       }
     };
@@ -159,7 +159,7 @@
     var commandsHaveLeadingDot;
     commandsHaveLeadingDot = repl.commands['.help'] != null;
     if (commandsHaveLeadingDot) {
-      return "." + commandName;
+      return `.${commandName}`;
     } else {
       return commandName;
     }
diff --git a/lib/coffee-script/scope.js b/lib/coffee-script/scope.js
index 460766564d..99e1d4a239 100644
--- a/lib/coffee-script/scope.js
+++ b/lib/coffee-script/scope.js
@@ -74,9 +74,9 @@
         newCode = startCode + index % (diff + 1);
         letter = String.fromCharCode(newCode);
         num = Math.floor(index / (diff + 1));
-        return "" + letter + (num || '');
+        return `${letter}${num || ''}`;
       } else {
-        return "" + name + (index || '');
+        return `${name}${index || ''}`;
       }
     };
 
@@ -143,7 +143,7 @@
       for (i = 0, len = ref.length; i < len; i++) {
         v = ref[i];
         if (v.type.assigned) {
-          results.push(v.name + " = " + v.type.value);
+          results.push(`${v.name} = ${v.type.value}`);
         }
       }
       return results;
diff --git a/lib/coffee-script/sourcemap.js b/lib/coffee-script/sourcemap.js
index aad4369b83..2bbbf82c78 100644
--- a/lib/coffee-script/sourcemap.js
+++ b/lib/coffee-script/sourcemap.js
@@ -136,7 +136,7 @@
 
     SourceMap.prototype.encodeBase64 = function(value) {
       return BASE64_CHARS[value] || (function() {
-        throw new Error("Cannot Base64 encode value: " + value);
+        throw new Error(`Cannot Base64 encode value: ${value}`);
       })();
     };
 
diff --git a/src/nodes.coffee b/src/nodes.coffee
index 81016d47ba..a3fcf70561 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -764,7 +764,6 @@ exports.TaggedTemplateCall = class TaggedTemplateCall extends Call
     super variable, [ arg ], soak
 
   compileNode: (o) ->
-    o.inTaggedTemplateCall = yes # Tell StringWithInterpolations whether to compile as ES2015 or not; remove in CoffeeScript 2
     @variable.compileToFragments(o, LEVEL_ACCESS).concat @args[0].compileToFragments(o, LEVEL_LIST)
 
 #### Extends
@@ -2236,24 +2235,20 @@ exports.Parens = class Parens extends Base
 
 #### StringWithInterpolations
 
-# Strings with interpolations are in fact just a variation of `Parens` with
-# string concatenation inside.
+exports.StringWithInterpolations = class StringWithInterpolations extends Base
+  constructor: (@body) ->
+
+  children: ['body']
 
-exports.StringWithInterpolations = class StringWithInterpolations extends Parens
-  # Uncomment the following line in CoffeeScript 2, to allow all interpolated
-  # strings to be output using the ES2015 syntax:
-  # unwrap: -> this
+  # `unwrap` returns `this` to stop ancestor nodes reaching in to grab @body,
+  # and using @body.compileNode. `StringWithInterpolations.compileNode` is
+  # _the_ custom logic to output interpolated strings as code.
+  unwrap: -> this
+
+  isComplex : -> @body.isComplex()
 
   compileNode: (o) ->
-    # This method produces an interpolated string using the new ES2015 syntax,
-    # which is opt-in by using tagged template literals. If this
-    # StringWithInterpolations isn’t inside a tagged template literal,
-    # fall back to the CoffeeScript 1.x output.
-    # (Remove this check in CoffeeScript 2.)
-    unless o.inTaggedTemplateCall
-      return super
-
-    # Assumption: expr is Value>StringLiteral or Op
+    # Assumes that `expr` is `Value` » `StringLiteral` or `Op`
     expr = @body.unwrap()
 
     elements = []