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.
Features
- Full support for ECMAScript 2016 (ECMA-262 7th 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 (~1300 unit tests with full code coverage)
API
Esprima can be used to perform lexical analysis (tokenization) or syntactic analysis (parsing) of a JavaScript programs.
A simple example:
var esprima = require('esprima');
var code = 'const answer = 42';
var tokens = esprima.tokenize(code);
var ast = esprima.parse(code);which gives a list of tokens:
[ { type: 'Keyword', value: 'const' },
{ type: 'Identifier', value: 'answer' },
{ type: 'Punctuator', value: '=' },
{ type: 'Numeric', value: '42' } ]and an abstract syntax tree:
{ type: 'Program',
body:
[ { type: 'VariableDeclaration',
declarations: [Object],
kind: 'const' } ],
sourceType: 'script' }