Edit

@babel/preset-stage-3

As of Babel v7, all of the stage-x presets have been deprecated. Check the blog post for more information.

For a more automatic migration, we have updated babel-upgrade to do this for you (you can run npx babel-upgrade).

If you want the same configuration as before:

{
  plugins: [
    // Stage 3
    "@babel/plugin-syntax-dynamic-import",
    "@babel/plugin-syntax-import-meta",
    ["@babel/plugin-proposal-class-properties", { loose: false }],
    "@babel/plugin-proposal-json-strings",
  ],
}

If you're using the same configuration across many separate projects, keep in mind that you can also create your own custom presets with whichever plugins and presets you're looking to use.

module.exports = function() {
  return {
    plugins: [
      require("@babel/plugin-syntax-dynamic-import"),
      [require("@babel/plugin-proposal-class-properties"), { loose: false }],
    ],
    presets: [
      // ...
    ],
  };
};

The gist of Stage 3 is:

Stage 3: candidate

What is it? The proposal is mostly finished and now needs feedback from implementations and users to progress further.

What’s required? The spec text must be complete. Designated reviewers (appointed by TC39, not by the champion) and the ECMAScript spec editor must sign off on the spec text. There must be at least two spec-compliant implementations (which don’t have to be enabled by default).

What’s next? Henceforth, changes should only be made in response to critical issues raised by the implementations and their use.

Install

npm install --save-dev @babel/preset-stage-3

Usage

Via .babelrc (Recommended)

.babelrc

{
  "presets": ["@babel/preset-stage-3"]
}

Via CLI

babel script.js --presets @babel/preset-stage-3

Via Node API

require("@babel/core").transform("code", {
  presets: ["@babel/preset-stage-3"],
});

Options

loose

boolean, defaults to false.

Enable "loose" transformations for any plugins in this preset that allow them.

useBuiltIns

boolean, defaults to false.

Will use the native built-in instead of trying to polyfill behavior for any plugins that require one.

References

• Chapter "The TC39 process for ECMAScript features" in "Exploring ES2016 and ES2017" by Axel Rauschmayer