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问题:
I have a React project which uses Webpack as the module bundler, and babel-loader to transform it into ES5, using the following settings:
module: { rules: [ { test: /\.jsx?$/, exclude: /node_modules/, use: [ { loader: "babel-loader" } ] } ] },
The options are set in a stand-alone .babelrc file.
Babel 6.13.0 supports ECMAScript modules, which means ECMAScript modules doesn't need to be transformed into CommonJS modules first. To get this behaviour, the documentation says that we should use this setting in our .babelrc.
{ presets: [["es2015", { "modules": false }], "react"] }
However, when I try to run Webpack using this setting, it comes back with the error:
$ ./node_modules/.bin/webpack /home/d4nyll/foo/bar/webpack.config.babel.js:1 (function (exports, require, module, __filename, __dirname) { import webpack from 'webpack'; ^^^^^^ SyntaxError: Unexpected token import
I'm guessing this is because babel-loader doesn't act on webpack.config.babel.js, and so it's not recognising the import keyword. The error does not appear when { "modules": false } is removed, but I want that functionality. How can I get Babel to recognise webpack.config.babel.js?
回答1:
The following worked for me.
Set .babelrc to the following:
{ "presets": ["es2015"] }
The .babelrc settings would apply to the webpack.config.babel.js file.
Next, change the Webpack configuration to include the options you want applied to your application code.
module: { rules: [ { test: /\.jsx?$/, exclude: /node_modules/, use: [ { loader: "babel-loader", options: { "presets": [["es2015", {"modules": false}], "react"] } } ] } ] },
回答2:
Just to emphasize, as you probably know: Your error
`Unexpected token import` in `webpack.config.babel.js`...
has nothing to do with the thing you are building, solely with your webpack.config.babel.js. Despite its name, ES6 is not gonna work without a few things made sure.
Things to make sure:
1) you don't need any webpack.config.js, when you have a webpack.config.babel.js in your project.
2) make sure in your package.json, you are on Webpack Version 3 or higher for (1) to hold true
3) make sure you have a .babelrc containing at least env or es2015
{ "presets": ["env"] }
4) make sure to have the following two installed
npm install babel-cli --save-dev npm install babel-preset-env --save-dev
Respectively babel-preset-es2015 depending on your .babelrc. (read here why env is arguably a bit cooler.)
回答3:
If you are using Webpack 2.6+ where import is baked in, make sure you use this babel plugin: https://www.npmjs.com/package/babel-plugin-syntax-dynamic-import
回答4:
You have created a webpack.config.js and when tying to execute webpack you are getting above error. Cause your webpack config file need to be babelified before you can use it,
1) Rename your webpack.config.js to webpack.config.babel.js.
2) Now create a new file webpack.config.js with just the following 2 lines
require('babel-register'); module.exports = require('./webpack.config.babel.js');
3) create a .babelrc file in parallel to your webpack.config.js file with following content. We need to tell babel explicitly what preset to use.
{ "presets": ["latest",'react', 'es2015','stage-2'] }
4) add following node modules to your dependency ( Required for presets used in .babelrc)
npm install babel-preset-env babel-preset-es2015 babel-preset-stage-2 babel-preset-latest babel-preset-react --save-dev
5) You are done . Now if you execute webpack --progress --colors --watch it should work.
