feat(TS): add support for TypeScript linting

BREAKING CHANGE: TypeScript v4 is required now (if you're using TS)

Author: kentcdodds

package.json

@@ -53,15 +53,15 @@
     "babel-plugin-module-resolver": "^4.0.0",
     "babel-plugin-transform-inline-environment-variables": "^0.4.3",
     "babel-plugin-transform-react-remove-prop-types": "^0.4.24",
-    "browserslist": "^4.14.6",
+    "browserslist": "^4.14.7",
     "chalk": "^4.1.0",
     "concurrently": "^5.3.0",
     "cosmiconfig": "^7.0.0",
     "cross-env": "^7.0.2",
     "cross-spawn": "^7.0.3",
     "doctoc": "^1.4.0",
-    "eslint": "^7.12.1",
-    "eslint-config-kentcdodds": "^16.1.0",
+    "eslint": "^7.13.0",
+    "eslint-config-kentcdodds": "^17.0.0",
     "eslint-config-prettier": "^6.15.0",
     "glob": "^7.1.6",
     "husky": "^4.3.0",
@@ -84,7 +84,7 @@
     "rollup-plugin-terser": "^7.0.2",
     "semver": "^7.3.2",
     "which": "^2.0.2",
-    "yargs-parser": "^20.2.3"
+    "yargs-parser": "^20.2.4"
   },
   "eslintConfig": {
     "extends": [

src/scripts/__tests__/__snapshots__/lint.js.snap

@@ -1,21 +1,23 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`lint --no-cache will disable caching 1`] = `eslint --config ./src/config/eslintrc.js --ignore-path ./src/config/eslintignore --no-cache .`;
+exports[`lint --no-cache will disable caching 1`] = `eslint --config ./src/config/eslintrc.js --ext js,ts,tsx --ignore-path ./src/config/eslintignore --no-cache .`;
 
-exports[`lint calls eslint CLI with default args 1`] = `eslint --config ./src/config/eslintrc.js --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
+exports[`lint calls eslint CLI with default args 1`] = `eslint --config ./src/config/eslintrc.js --ext js,ts,tsx --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
 
-exports[`lint does not use built-in config with .eslintrc file 1`] = `eslint --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
+exports[`lint does not use built-in config with .eslintrc file 1`] = `eslint --ext js,ts,tsx --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
 
-exports[`lint does not use built-in config with .eslintrc.js file 1`] = `eslint --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
+exports[`lint does not use built-in config with .eslintrc.js file 1`] = `eslint --ext js,ts,tsx --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
 
-exports[`lint does not use built-in config with --config 1`] = `eslint --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache --config ./custom-config.js .`;
+exports[`lint does not use built-in config with --config 1`] = `eslint --ext js,ts,tsx --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache --config ./custom-config.js .`;
 
-exports[`lint does not use built-in config with eslintConfig pkg prop 1`] = `eslint --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
+exports[`lint does not use built-in config with eslintConfig pkg prop 1`] = `eslint --ext js,ts,tsx --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
 
-exports[`lint does not use built-in ignore with .eslintignore file 1`] = `eslint --config ./src/config/eslintrc.js --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
+exports[`lint does not use built-in ignore with .eslintignore file 1`] = `eslint --config ./src/config/eslintrc.js --ext js,ts,tsx --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
 
-exports[`lint does not use built-in ignore with --ignore-path 1`] = `eslint --config ./src/config/eslintrc.js --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache --ignore-path ./my-ignore .`;
+exports[`lint does not use built-in ignore with --ignore-path 1`] = `eslint --config ./src/config/eslintrc.js --ext js,ts,tsx --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache --ignore-path ./my-ignore .`;
 
-exports[`lint does not use built-in ignore with eslintIgnore pkg prop 1`] = `eslint --config ./src/config/eslintrc.js --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
+exports[`lint does not use built-in ignore with eslintIgnore pkg prop 1`] = `eslint --config ./src/config/eslintrc.js --ext js,ts,tsx --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache .`;
 
-exports[`lint runs on given files, but only js files 1`] = `eslint --config ./src/config/eslintrc.js --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache ./src/index.js ./src/component.js`;
+exports[`lint runs on given files, but only js files 1`] = `eslint --config ./src/config/eslintrc.js --ext js,ts,tsx --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache ./src/index.js ./src/thing.ts ./src/lib.tsx ./src/component.js`;
+
+exports[`lint supports custom --ext 1`] = `eslint --config ./src/config/eslintrc.js --ignore-path ./src/config/eslintignore --cache --cache-location <PROJECT_ROOT>/node_modules/.cache/.eslintcache --ext js .`;

src/scripts/__tests__/lint.js

@@ -75,11 +75,16 @@ cases(
     '--no-cache will disable caching': {
       args: ['--no-cache'],
     },
+    'supports custom --ext': {
+      args: ['--ext', 'js'],
+    },
     'runs on given files, but only js files': {
       args: [
         './src/index.js',
         './package.json',
         './src/index.css',
+        './src/thing.ts',
+        './src/lib.tsx',
         './src/component.js',
       ],
     },

src/scripts/lint.js

@@ -18,6 +18,10 @@ const config = useBuiltinConfig
   ? ['--config', hereRelative('../config/eslintrc.js')]
   : []
 
+const defaultExtensions = 'js,ts,tsx'
+const ext = args.includes('--ext') ? [] : ['--ext', defaultExtensions]
+const extensions = (parsedArgs.ext || defaultExtensions).split(',')
+
 const useBuiltinIgnore =
   !args.includes('--ignore-path') &&
   !hasFile('.eslintignore') &&
@@ -43,12 +47,14 @@ if (filesGiven) {
   // we need to take all the flag-less arguments (the files that should be linted)
   // and filter out the ones that aren't js files. Otherwise json or css files
   // may be passed through
-  args = args.filter(a => !parsedArgs._.includes(a) || /\.jsx?$/.test(a))
+  args = args.filter(
+    a => !parsedArgs._.includes(a) || extensions.some(e => a.endsWith(e)),
+  )
 }
 
 const result = spawn.sync(
   resolveBin('eslint'),
-  [...config, ...ignore, ...cache, ...args, ...filesToApply],
+  [...config, ...ext, ...ignore, ...cache, ...args, ...filesToApply],
   {stdio: 'inherit'},
 )