babel/packages/babylon/README.md

Babylon is a JavaScript parser used in Babel.

• ES6 enabled by default.
• Comment attachment.
• Support for JSX and Flow.
• Support for experimental language proposals.

Credits

Heavily based on acorn and acorn-jsx, thanks to the awesome work of @RReverser and @marijnh.

Significant diversions are expected to occur in the future such as streaming, EBNF definitions, sweet.js integration, interspacial parsing and more.

API

babylon.parse(code, [options])

Options

• allowImportExportEverywhere: By default, import and export declarations can only appear at a program's top level. Setting this option to true allows them anywhere where a statement is allowed.

• allowReturnOutsideFunction: By default, a return statement at the top level raises an error. Set this to true to accept such code.

• sourceType: Indicate the mode the code should be parsed in. Can be either "script" or "module".

• features: Object containing names of all the proposed syntax you want to support.

• plugins: Object containg the plugins that you want to enable.

Example

require("babylon").parse("code", {
  // parse in strict mode and allow module declarations
  sourceType: "module",

  features: {
    // enable experimental async functions
    asyncFunctions: true
  }

  plugins: {
    // enable jsx and flow syntax
    jsx: true,
    flow: true
  }
});

Features

• asyncFunctions
• doExpressions
• comprehensions
• trailingFunctionCommas
• objectRestSpread
• decorators

Plugins

• jsx
• flow