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esprima
Advanced tools
ECMAScript parsing infrastructure for multipurpose analysis
Weekly downloads
Package description
Esprima is a high performance, standard-compliant ECMAScript parser written in ECMAScript (also popularly known as JavaScript). It is capable of parsing JavaScript code to produce an abstract syntax tree (AST), which can be used for various purposes such as static analysis, code instrumentation, and transformation.
Parsing JavaScript Code
This feature allows you to parse a string of JavaScript code and obtain an abstract syntax tree (AST) that represents the structure of the code.
const esprima = require('esprima');
const program = 'const answer = 42;';
const ast = esprima.parseScript(program);
Syntax Tree Analysis
Once you have the AST, you can analyze it to extract information about the code, such as variable names, function declarations, and more.
const esprima = require('esprima');
const program = 'const answer = 42;';
const ast = esprima.parseScript(program);
console.log(ast.body[0].declarations[0].id.name); // 'answer'
Tokenization
Esprima can also be used to tokenize JavaScript code, breaking it down into its lexical components (tokens) such as keywords, identifiers, literals, and operators.
const esprima = require('esprima');
const program = 'const answer = 42;';
const tokens = esprima.tokenize(program);
console.log(tokens);
Acorn is a tiny, fast JavaScript parser, also producing an AST. It is similar to Esprima in terms of functionality but focuses on being smaller and more modular.
Babel-parser (previously known as babylon) is the JavaScript parser used by Babel. It extends the functionality of Esprima by supporting experimental JavaScript features and JSX, which is useful for React development.
Cherow is a very fast, standards-compliant, self-hosted JavaScript parser with error recovery. It compares to Esprima in terms of compliance and performance but also offers better error handling and recovery options.
Readme
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.
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.
FAQs
ECMAScript parsing infrastructure for multipurpose analysis
The npm package esprima receives a total of 33,518,279 weekly downloads. As such, esprima popularity was classified as popular.
We found that esprima demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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