eslint-scope
Advanced tools
Package description
The eslint-scope npm package is used to analyze the scope of variables within JavaScript code. It is part of the ESLint family of tools and is used to determine where variables are declared and how they are used throughout the code. This can be particularly useful for identifying issues with variable shadowing, undeclared variables, or potential scope leaks.
Analyzing variable scope in a JavaScript file
This code sample demonstrates how to use eslint-scope to analyze the scope of variables in a JavaScript file. It reads the file, parses it into an AST (Abstract Syntax Tree) using espree, and then analyzes the scope with eslint-scope. The resulting globalScope object contains information about the variables and references in the global scope of the file.
const eslintScope = require('eslint-scope');
const espree = require('espree');
const fs = require('fs');
const code = fs.readFileSync('myfile.js', 'utf8');
const ast = espree.parse(code, { ecmaVersion: 6 });
const scopeManager = eslintScope.analyze(ast);
const globalScope = scopeManager.globalScope;
// Inspect the variables and references in the global scope
console.log(globalScope.variables);
console.log(globalScope.references);Escope is another scope analysis tool for JavaScript. It is similar to eslint-scope but is no longer actively maintained. Escope was the predecessor to eslint-scope and served a similar purpose in analyzing variable scope within JavaScript code.
Jscodeshift is a toolkit for running codemods over multiple JavaScript or TypeScript files. It uses a different approach but can be used for similar scope analysis and transformation tasks. Jscodeshift provides a more extensive API for manipulating the AST and is often used for large-scale codebase refactors.
Babel-traverse allows you to traverse and manipulate the AST generated by Babel. While its primary use is for Babel plugins and transformations, it can also be used to analyze scope and variable declarations in a manner similar to eslint-scope. Babel-traverse is part of the larger Babel ecosystem, which is widely used for JavaScript compilation and transformation.
Changelog
7.2.1 (2023-05-31)
v7.2.0 - April 13, 2023
70c8db1 feat: Add isGlobalReturn method on scopeManager. (#96) (Nicholas C. Zakas)3dbad80 chore: add triage action (#95) (Milos Djermanovic)34ffedc ci: add Node v19 (#94) (Milos Djermanovic)4c00534 ci: update Github actions (#93) (Deepshika S)6c8ccf2 chore: add funding field (#92) (Deepshika S)a8811b8 build: add node v18 (#91) (唯然)25abacf docs: add badges (#89) (Milos Djermanovic)v7.1.1 - February 11, 2022
8938109 chore: upgrade espree@9.3.1 eslint-visitor-keys@3.3.0 (#88) (Milos Djermanovic)4e1d24c fix: ignore "use strict" directives in ES3 (#87) (Milos Djermanovic)ceb8bdd ci: use node v16 (#84) (Nitin Kumar)62e147b test: add tests with year-based ecmaVersion (#83) (Milos Djermanovic)v7.1.0 - November 20, 2021
d756f1e feat: Add sourceType:commonjs support (#81) (Nicholas C. Zakas)v7.0.0 - November 16, 2021
22a55c0 feat!: support class static blocks (#80) (Milos Djermanovic)4aafb61 build: upgrade eslint-release to v3.2.0 to support conventional commits (#79) (Milos Djermanovic)263c762 Build: add node v17 (#76) (唯然)v6.0.0 - July 23, 2021
4ee1d80 Fix: Ensure correct version in package (#73) (Nicholas C. Zakas)82a7e6d Breaking: Switch to ESM (fixes #70) (#71) (Brett Zamir)0b4a5f1 Update: support class fields (refs eslint/eslint#14343) (#69) (Toru Nagashima)39f8cfc Chore: upgrade estraverse to version 5 (#68) (Rouven Weßling)ae27ff3 Docs: Add range to espree options in README (fixes #66) (#67) (Alan Liang)v5.1.1 - September 12, 2020
9b528d7 Upgrade: esrecurse version to ^4.3.0 (#64) (Timofey Kachalov)f758bbc Chore: fix definiton -> definition typo in comments (#63) (Kevin Kirsche)7513734 Chore: move to GitHub Actions (#62) (Kai Cataldo)v5.1.0 - June 4, 2020
d4a3764 Update: support new export syntax (#56) (Toru Nagashima)v5.0.0 - July 20, 2019
e9fa22e Upgrade: update dependencies after dropping support for Node <8 (#53) (Kai Cataldo)ee9f7c1 Breaking: drop support for Node v6 (#54) (Kai Cataldo)v4.0.3 - March 15, 2019
299df64 Fix: arrow function scope strictness (take 2) (#52) (futpib)v4.0.2 - March 1, 2019
c925600 Revert "Fix: Arrow function scope strictness (fixes #49) (#50)" (#51) (Teddy Katz)v4.0.1 - March 1, 2019
2533966 Fix: Arrow function scope strictness (fixes #49) (#50) (futpib)0cbeea5 Chore: add supported Node.js versions to CI (#47) (Kai Cataldo)b423057 Upgrade: eslint-release@1.0.0 (#46) (Teddy Katz)v4.0.0 - June 21, 2018
v4.0.0-rc.0 - June 9, 2018
v4.0.0-alpha.0 - April 27, 2018
v3.7.1 - April 12, 2017
v3.7.0 - March 17, 2017
Readme
ESLint Scope is the ECMAScript scope analyzer used in ESLint. It is a fork of escope.
npm i eslint-scope --save
To use in an ESM file:
import * as eslintScope from 'eslint-scope';
To use in a CommonJS file:
const eslintScope = require('eslint-scope');
Example:
import * as eslintScope from 'eslint-scope';
import * as espree from 'espree';
import estraverse from 'estraverse';
const ast = espree.parse(code, { range: true });
const scopeManager = eslintScope.analyze(ast);
const currentScope = scopeManager.acquire(ast); // global scope
estraverse.traverse(ast, {
enter (node, parent) {
// do stuff
if (/Function/.test(node.type)) {
currentScope = scopeManager.acquire(node); // get current function scope
}
},
leave(node, parent) {
if (/Function/.test(node.type)) {
currentScope = currentScope.upper; // set to parent scope
}
// do stuff
}
});
Issues and pull requests will be triaged and responded to as quickly as possible. We operate under the ESLint Contributor Guidelines, so please be sure to read them before contributing. If you're not sure where to dig in, check out the issues.
npm test - run all linting and testsnpm run lint - run all lintingESLint Scope is licensed under a permissive BSD 2-clause license.
FAQs
ECMAScript scope analyzer for ESLint
The npm package eslint-scope receives a total of 53,295,725 weekly downloads. As such, eslint-scope popularity was classified as popular.
We found that eslint-scope demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 4 open source maintainers collaborating on the project.
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