Esprima (esprima.org, BSD license) is a high performance, standard-compliant ECMAScript parser written in ECMAScript (also popularly known as JavaScript). Esprima is created and maintained by Ariya Hidayat, with the help of many contributors.

• Full support for ECMAScript 2017 (ECMA-262 8th Edition)
• Sensible syntax tree format as standardized by ESTree project
• Experimental support for JSX, a syntax extension for React
• Optional tracking of syntax node location (index-based and line-column)
• Heavily tested (~1500 unit tests with full code coverage)

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

For more information, please read the complete documentation.