babylon

Babylon is a JavaScript parser used in Babel.

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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, interspatial parsing and more.

API

babylon.parse(code, [options])

babylon.parseExpression(code, [options])

parse() parses the provided code as an entire ECMAScript program, while parseExpression() tries to parse a single Expression with performance in mind. When in doubt, use .parse().

Options

Output

Babylon generates AST according to Babel AST format. It is based on ESTree spec with the following deviations:

There is now an estree plugin which reverts these deviations

AST for JSX code is based on Facebook JSX AST with the addition of one node type:

Semver

Babylon follows semver in most situations. The only thing to note is that some spec-compliancy bug fixes may be released under patch versions.

For example: We push a fix to early error on something like #107 - multiple default exports per file. That would be considered a bug fix even though it would cause a build to fail.

Example

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

  plugins: [
    // enable jsx and flow syntax
    "jsx",
    "flow"
  ]
});

Plugins