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babel-loader
Advanced tools
The babel-loader npm package is a Webpack plugin that integrates Babel with Webpack. Babel is a JavaScript compiler that allows you to use next-generation JavaScript, today. It compiles ES6 and beyond into ES5 code that can run in current browser environments. babel-loader enables Webpack to process and bundle JavaScript files using Babel.
Transpiling ES6+ to ES5
This feature allows developers to write modern JavaScript code without worrying about compatibility issues with older browsers. The code sample shows a Webpack configuration that uses babel-loader to process files ending in .js, excluding node_modules, and transpiles them using the preset '@babel/preset-env'.
module.exports = {
module: {
rules: [
{
test: /\.js$/,
exclude: /node_modules/,
use: {
loader: 'babel-loader',
options: {
presets: ['@babel/preset-env']
}
}
}
]
}
};
Using Babel plugins
babel-loader can be configured to use specific Babel plugins to enable experimental features or custom transformations. The code sample demonstrates how to include the '@babel/plugin-proposal-class-properties' plugin to allow the use of class properties syntax in JavaScript.
module.exports = {
module: {
rules: [
{
test: /\.js$/,
exclude: /node_modules/,
use: {
loader: 'babel-loader',
options: {
plugins: ['@babel/plugin-proposal-class-properties']
}
}
}
]
}
};
Source Maps support
babel-loader supports source maps, which help in debugging transpiled code by mapping the transformed code back to the original source code. The code sample shows how to enable source maps in the babel-loader options.
module.exports = {
module: {
rules: [
{
test: /\.js$/,
use: {
loader: 'babel-loader',
options: {
sourceMaps: true
}
}
}
]
}
};
ts-loader is a Webpack loader for TypeScript, similar to how babel-loader works for JavaScript. It compiles TypeScript code to JavaScript, allowing developers to use TypeScript's static typing features. While babel-loader focuses on JavaScript and its newer syntax, ts-loader is specifically designed for TypeScript.
awesome-typescript-loader is another Webpack loader for TypeScript, providing similar functionality to ts-loader. It also compiles TypeScript to JavaScript and offers features like Babel integration and type checking. It is known for being fast and providing a smoother integration with Babel compared to ts-loader.
esbuild-loader is a Webpack loader that uses the esbuild bundler. It is designed for extremely fast bundling and minifying of JavaScript and TypeScript code. Unlike babel-loader, which focuses on compatibility and syntax transformations, esbuild-loader emphasizes performance and speed.
Turn ES6 code into vanilla ES5 with no runtime required using babel;
$ npm install --save-dev babel-loader
import Animal from 'babel!./Animal.js';
class Person extends Animal {
constructor(arg='default') {
this.eat = 'Happy Meal';
}
}
export default Person;
var Person = require('babel!./Person.js').default;
new Person();
Or within the webpack config:
module: {
loaders: [
{ test: /\.js$/, exclude: /node_modules/, loader: 'babel-loader'}
]
}
and then import normally:
import Person from './Person.js';
Make sure you are transforming as few files as possible. Because you are probably
matching /\.js$/
, you might be transforming the node_modules
folder or other unwanted
source. See the exclude
option in the loaders
config as documented above.
babel uses very small helpers for common functions such as _extend
. By default
this will be added to every file that requires it.
You can instead require the babel runtime as a separate module to avoid the duplication.
The following configuration disables automatic per-file runtime injection in babel, instead
requiring babel-runtime
and making all helper references use it.
See the docs for more information.
NOTE: You must run npm install babel-runtime --save
to include this in your project.
loaders: [
// the optional 'runtime' transformer tells babel to require the runtime instead of inlining it.
{ test: /\.jsx?$/, exclude: /node_modules/, loader: 'babel-loader?experimental&optional=runtime' }
]
See the babel
options
MIT © Luis Couto
FAQs
babel module loader for webpack
We found that babel-loader demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 5 open source maintainers collaborating on the project.
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