Remove targets from library preset to force es2015 target (#1322)

* Remove targets from library preset to force es2015 target

* Remove forceAllTransforms

* Support settings compile targets as top-level option in library preset

packages/library/README.md

@@ -17,6 +17,12 @@
 - Automatically marks dependencies as external
 - Easily extensible to customize your library as needed
 
+**Important! This preset does not include 
+@babel/polyfill for size reasons. If you need
+polyfills in your library code, consider 
+importing @babel/polyfill, core-js, or other 
+alternative.**
+
 ## Requirements
 
 - Node.js ^8.10 or 10+
@@ -243,15 +249,17 @@ module.exports = {
 
       // Disable cleaning the output build directory
       clean: false,
+
+      // Target specific browsers or Node.js versions with @babel/preset-env
+      targets: {},
 
       // Add additional Babel plugins, presets, or env options
       babel: {
         // Override options for @babel/preset-env
         presets: [
           ['@babel/preset-env', {
-            // Passing in browser targets to @babel/preset-env will replace them
-            // instead of merging them when using the 'web' target
-            targets: { browsers: 'ie 9' }
+            debug: neutrino.options.debug,
+            useBuiltIns: 'entry'
           }]
         ]
       }
@@ -260,7 +268,7 @@ module.exports = {
 };
 ```
 
-_Example: Override the library Babel compilation target to Node.js v6 and commonjs2 module:_
+_Example: Override the library to output a commonjs2 module:_
 
 ```js
 const library = require('@neutrinojs/library');
@@ -270,23 +278,59 @@ module.exports = {
     library({
       name: 'Logger',
       target: 'node',
-      libraryTarget: 'commonjs2',
-      // Add additional Babel plugins, presets, or env options
-      babel: {
-        // Override options for @babel/preset-env
-        presets: [
-          ['@babel/preset-env', {
-            targets: {
-              node: '6.0'
-            }
-          }]
-        ]
+      libraryTarget: 'commonjs2'
+    })
+  ]
+};
+```
+
+### Targets
+
+Using the `targets` option, you can target specific browsers or Node.js versions
+to compile to with `@babel/preset-env`. By default, this preset does not set any
+targets and will compile to an ES5 baseline.
+
+_Example: Override the library Babel compilation target to Node.js v6:_
+
+```js
+const library = require('@neutrinojs/library');
+
+module.exports = {
+  use: [
+    library({
+      name: 'Logger',
+      target: 'node',
+      targets: {
+        node: '6.0'
       }
     })
   ]
 };
 ```
 
+Setting to `false` will override Neutrino's default targets and allow
+`@babel/preset-env` to read targets from a [`.browserslistrc` file](https://babeljs.io/docs/en/babel-preset-env#browserslist-integration).
+
+```js
+const library = require('@neutrinojs/library');
+
+module.exports = {
+  use: [
+    library({
+      name: 'Logger',
+      target: 'node',
+      targets: false
+    })
+  ]
+};
+```
+
+When using a `.browserslistrc` file, be aware that file changes may not
+invalidate cache as expected: https://github.com/babel/babel-loader/issues/690
+
+See [`@babel/preset-env`](https://babeljs.io/docs/en/babel-preset-env#targets)
+for all other available settings.
+
 ## Customizing
 
 To override the build configuration, start with the documentation on [customization](https://neutrinojs.org/customization/).

packages/library/index.js

@@ -24,9 +24,14 @@ module.exports = (opts = {}) => {
       target: 'web',
       libraryTarget: 'umd',
       babel: {},
-      externals: {}
+      externals: {},
+      targets: {}
     }, opts);
 
+    if (options.targets === false) {
+      options.targets = {};
+    }
+
     Object.assign(options, {
       babel: babelMerge({
         plugins: [
@@ -36,9 +41,7 @@ module.exports = (opts = {}) => {
           [require.resolve('@babel/preset-env'), {
             debug: neutrino.options.debug,
             useBuiltIns: 'entry',
-            targets: options.target === 'node' ?
-              { node: '8.10' } :
-              { browsers: 'ie 9' }
+            targets: options.targets
           }]
         ]
       }, options.babel)

packages/library/test/library_test.js

@@ -119,6 +119,32 @@ test('valid preset commonjs2 libraryTarget', t => {
   t.is(errors.length, 0);
 });
 
+test('targets option test', t => {
+  const api = new Neutrino();
+  const targets = {
+    browsers: ['last 2 iOS versions']
+  };
+
+  api.use(mw({ name: 'alpha', targets }));
+
+  t.deepEqual(api.config.module
+    .rule('compile')
+    .use('babel')
+    .get('options')
+    .presets[0][1].targets, targets);
+});
+
+test('targets false option test', t => {
+  const api = new Neutrino();
+  api.use(mw({ name: 'alpha', targets: false }));
+
+  t.deepEqual(api.config.module
+    .rule('compile')
+    .use('babel')
+    .get('options')
+    .presets[0][1].targets, {});
+});
+
 test('updates lint config by default when target is web', t => {
   const api = new Neutrino();
   api.use(lint());