jquery/esprima

★ 7,137TypeScriptAudience · developerComplexity · 2/5LicenseSetup · easy

Mindmap

mindmap
  root((repo))
    What it does
      Parse JavaScript
      Build syntax trees
      ESTree compatible
    Supported syntax
      ES2019 standard
      JSX experimental
    Tech Stack
      TypeScript
      Node.js
      npm
    Use Cases
      Build linters
      Analyze code structure
      Transform JavaScript

mindmap root((repo)) What it does Parse JavaScript Build syntax trees ESTree compatible Supported syntax ES2019 standard JSX experimental Tech Stack TypeScript Node.js npm Use Cases Build linters Analyze code structure Transform JavaScript

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Things people build with this

USE CASE 1

Parse a JavaScript file to extract all function names and build a table of contents

USE CASE 2

Build a linter rule that flags a specific coding pattern across your codebase

USE CASE 3

Analyze a codebase to find unused variables by walking the syntax tree

USE CASE 4

Transform JavaScript source code by modifying the parsed tree and printing it back

Tech stack

TypeScriptJavaScriptNode.jsnpm

Getting it running

Difficulty · easy Time to first run · 5min

Use freely for any purpose, including commercial use, as long as you keep the copyright notice.

In plain English

Esprima is a JavaScript parser: a tool that reads JavaScript code and breaks it down into a structured representation that other programs can analyze. When you write JavaScript, it is just text. A parser turns that text into a tree of objects that describes the code's structure, showing which parts are variable declarations, which are function calls, which are loops, and so on. This tree format is called an abstract syntax tree. Developers use parsers like Esprima as a building block for tools that work with code programmatically. Linters that check code for style or errors, formatters that reformat code automatically, bundlers that combine files, and code analysis tools all typically rely on parsing JavaScript first. Esprima provides that foundation. The library supports JavaScript up to the ECMAScript 2019 standard, which is the version of JavaScript formalized that year. It also has experimental support for JSX, a syntax extension used in React applications that lets developers write HTML-like markup inside JavaScript. The output tree follows a standardized format maintained by the ESTree project, which means Esprima's output is compatible with many other tools that expect that format. Esprima is available as an npm package, so it can be installed with a standard JavaScript package manager and used in Node.js projects. It is maintained under the jQuery organization on GitHub and released under the BSD license, which permits free use in commercial and open-source projects. The README is brief, fuller documentation is available on the project's website.

Copy-paste prompts

Prompt 1

Using esprima, show me how to parse a JavaScript file and extract the names of every function declared in it.

Prompt 2

I want to walk every node in an esprima AST and find all variable declarations. Show me how to do that with a simple recursive visitor.

Prompt 3

How do I use esprima to check if a JavaScript string is valid syntax without running it?

Prompt 4

I am building a simple linter with esprima. Show me how to parse a file and flag any use of the eval function.

Prompt 5

Using esprima with JSX support enabled, parse a React component file and list all the JSX element types used in it.

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