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@babel/standalone

@babel/standalone provides a standalone build of Babel for use in browsers and other non-Node.js environments.

When (not) to use @babel/standalone

If you're using Babel in production, you should normally not use @babel/standalone. Instead, you should use a build system running on Node.js, such as Webpack, Rollup, or Parcel, to transpile your JS ahead of time.

However, there are some valid use cases for @babel/standalone:

  • It provides an easy, convenient way to prototype with Babel. Using @babel/standalone, you can get started using Babel with just a simple script tag in your HTML.
  • Sites that compile user-provided JavaScript in real-time, like JSFiddle, JS Bin, the REPL on the Babel site, JSitor, etc.
  • Apps that embed a JavaScript engine such as V8 directly, and want to use Babel for compilation
  • Apps that want to use JavaScript as a scripting language for extending the app itself, including all the goodies that ES2015 provides.
  • Other non-Node.js environments (ReactJS.NET, ruby-babel-transpiler, php-babel-transpiler, etc).

Installation

There are several ways to get a copy of @babel/standalone. Pick whichever one you like:

Script Tags

When loaded in a browser, @babel/standalone will automatically compile and execute all script tags with type text/babel or text/jsx:

<div id="output"></div>
<!-- Load Babel -->
<script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>
<!-- Your custom script here -->
<script type="text/babel">
const getMessage = () => "Hello World";
document.getElementById('output').innerHTML = getMessage();
</script>

If you want to use your browser's native support for ES Modules, you'd normally need to set a type="module" attribute on your script tag.

Added in: v7.10.0

With @babel/standalone, set a data-type="module" attribute instead, like this:

<script type="text/babel" data-type="module">

You can use the data-plugins and data-presets attributes to specify the Babel plugins/presets to use:

<script type="text/babel" data-presets="env,stage-3">

Loading external scripts via src attribute is supported too:

<script type="text/babel" src="foo.js"></script>

You can also set the async attribute for external scripts.

<script type="text/babel" src="foo.js" async></script>

API

Load babel.js or babel.min.js in your environment. This will expose Babel's API in a Babel object:

var input = 'const getMessage = () => "Hello World";';
var output = Babel.transform(input, { presets: ['env'] }).code;

Note that config files don't work in @babel/standalone, as no file system access is available. The presets and/or plugins to use must be specified in the options passed to Babel.transform.

Customization

custom plugins

Custom plugins and presets can be added using the registerPlugin and registerPreset methods respectively:

// Simple plugin that converts every identifier to "LOL"
function lolizer() {
  return {
    visitor: {
      Identifier(path) {
        path.node.name = 'LOL';
      }
    }
  }
}
Babel.registerPlugin('lolizer', lolizer);

Once registered, you can either use the custom plugin in an inline script:

<script type="text/babel" data-plugins="lolizer">

Or you can use the plugin with Babel.transform:

var output = Babel.transform(
  'function helloWorld() { alert(hello); }',
  {plugins: ['lolizer']}
);
// Returns "function LOL() { LOL(LOL); }"

custom presets: passing options to built-in presets/plugins

If you want to pass options to builtin plugins and presets, you can create a new preset and pass these options inside the preset.

// Define a preset
Babel.registerPreset("env-plus", {
  presets: [
    [Babel.availablePresets["env"], { "loose": true }]
  ],
  plugins: [
    [
      Babel.availablePlugins["proposal-decorators"], { decoratorsBeforeExport: true }
    ]
  ],
});

Once registered, you can use this preset in an inline script:

<script type="text/babel" data-presets="env-plus">