fix(error): remove throw in Error constructor to improve performance in IE11

lib/zone-spec/long-stack-trace.ts

@@ -58,7 +58,7 @@ function addErrorStack(lines: string[], error: Error): void {
 }
 
 function renderLongStackTrace(frames: LongStackTrace[], stack: string): string {
-  const longTrace: string[] = [stack.trim()];
+  const longTrace: string[] = [stack ? stack.trim() : ''];
 
   if (frames) {
     let timestamp = new Date().getTime();
@@ -97,26 +97,38 @@ function renderLongStackTrace(frames: LongStackTrace[], stack: string): string {
 
   onScheduleTask: function(
       parentZoneDelegate: ZoneDelegate, currentZone: Zone, targetZone: Zone, task: Task): any {
-    const currentTask = Zone.currentTask;
-    let trace = currentTask && currentTask.data && (currentTask.data as any)[creationTrace] || [];
-    trace = [new LongStackTrace()].concat(trace);
-    if (trace.length > this.longStackTraceLimit) {
-      trace.length = this.longStackTraceLimit;
+    if (Error.stackTraceLimit > 0) {
+      // if Error.stackTraceLimit is 0, means stack trace
+      // is disabled, so we don't need to generate long stack trace
+      // this will improve performance in some test(some test will
+      // set stackTraceLimit to 0, https://github.com/angular/zone.js/issues/698
+      const currentTask = Zone.currentTask;
+      let trace = currentTask && currentTask.data && (currentTask.data as any)[creationTrace] || [];
+      trace = [new LongStackTrace()].concat(trace);
+      if (trace.length > this.longStackTraceLimit) {
+        trace.length = this.longStackTraceLimit;
+      }
+      if (!task.data) task.data = {};
+      (task.data as any)[creationTrace] = trace;
     }
-    if (!task.data) task.data = {};
-    (task.data as any)[creationTrace] = trace;
     return parentZoneDelegate.scheduleTask(targetZone, task);
   },
 
   onHandleError: function(
       parentZoneDelegate: ZoneDelegate, currentZone: Zone, targetZone: Zone, error: any): boolean {
-    const parentTask = Zone.currentTask || error.task;
-    if (error instanceof Error && parentTask) {
-      const longStack =
-          renderLongStackTrace(parentTask.data && parentTask.data[creationTrace], error.stack);
-      try {
-        error.stack = (error as any).longStack = longStack;
-      } catch (err) {
+    if (Error.stackTraceLimit > 0) {
+      // if Error.stackTraceLimit is 0, means stack trace
+      // is disabled, so we don't need to generate long stack trace
+      // this will improve performance in some test(some test will
+      // set stackTraceLimit to 0, https://github.com/angular/zone.js/issues/698
+      const parentTask = Zone.currentTask || error.task;
+      if (error instanceof Error && parentTask) {
+        const longStack =
+            renderLongStackTrace(parentTask.data && parentTask.data[creationTrace], error.stack);
+        try {
+          error.stack = (error as any).longStack = longStack;
+        } catch (err) {
+        }
       }
     }
     return parentZoneDelegate.handleError(targetZone, error);
@@ -131,6 +143,9 @@ function captureStackTraces(stackTraces: string[][], count: number): void {
 }
 
 function computeIgnoreFrames() {
+  if (Error.stackTraceLimit <= 0) {
+    return;
+  }
   const frames: string[][] = [];
   captureStackTraces(frames, 2);
   const frames1 = frames[0];

lib/zone.ts

@@ -1630,16 +1630,6 @@ const Zone: ZoneType = (function(global: any) {
   function ZoneAwareError(): Error {
     // We always have to return native error otherwise the browser console will not work.
     let error: Error = NativeError.apply(this, arguments);
-    if (!error.stack) {
-      // in IE, the error.stack will be undefined
-      // when error was constructed, it will only
-      // be available when throw
-      try {
-        throw error;
-      } catch (err) {
-        error = err;
-      }
-    }
     // Save original stack trace
     const originalStack = (error as any)['originalStack'] = error.stack;
 

test/zone-spec/long-stack-trace-zone.spec.ts

@@ -103,7 +103,11 @@ describe('longStackTraceZone', function() {
         setTimeout(function() {
           let promise = new Promise(function(resolve, reject) {
             setTimeout(function() {
-              reject(new Error('Hello Promise'));
+              try {
+                throw new Error('Hello Promise');
+              } catch (err) {
+                reject(err);
+              }
             }, 0);
           });
           promise.catch(function(error) {
@@ -116,4 +120,23 @@ describe('longStackTraceZone', function() {
       }, 0);
     });
   });
+
+  it('should not produce long stack traces if Error.stackTraceLimit = 0', function(done) {
+    const originalStackTraceLimit = Error.stackTraceLimit;
+    lstz.run(function() {
+      setTimeout(function() {
+        setTimeout(function() {
+          setTimeout(function() {
+            if (log[0].stack) {
+              expectElapsed(log[0].stack, 1);
+            }
+            Error.stackTraceLimit = originalStackTraceLimit;
+            done();
+          }, 0);
+          Error.stackTraceLimit = 0;
+          throw new Error('Hello');
+        }, 0);
+      }, 0);
+    });
+  });
 });