Esprima

Esprima is a high performance, standard-compliant ECMAScript parser written in ECMAScript (also popularly known as JavaScript).

Features

Full support for ECMAScript 2016 (ECMA-262 7th Edition)
Sensible syntax tree format as standardized by EStree project
Optional tracking of syntax node location (index-based and line-column)
Experimental support for JSX, a syntax extension for React
Heavily tested (~1300 tests with full code coverage)

API

Esprima can be used to perform lexical analysis (tokenization) or syntactic analysis (parsing) of a JavaScript program.

A simple example on Node.js REPL:

> var esprima = require('esprima');
> var program = 'const answer = 42';

> esprima.tokenize(program);
[ { type: 'Keyword', value: 'const' },
  { type: 'Identifier', value: 'answer' },
  { type: 'Punctuator', value: '=' },
  { type: 'Numeric', value: '42' } ]

> esprima.parse(program);
{ type: 'Program',
  body:
   [ { type: 'VariableDeclaration',
       declarations: [Object],
       kind: 'const' } ],
  sourceType: 'script' }

Once the full syntax tree is obtained, various static code analysis can be applied to give an insight to the code: syntax visualization, code validation, editing autocomplete (with type inferencing) and many others.

Regenerating the code from the syntax tree permits a few different types of code transformation, from a simple rewriting (with specific formatting) to a more complicated minification.

Esprima runs on many popular web browsers, as well as other ECMAScript platforms such as Rhino, Nashorn, and Node.js. It is distributed under the BSD license.

ECMAScript parsing infrastructure for multipurpose analysis

Features

API