92 lines
3.6 KiB
Markdown
92 lines
3.6 KiB
Markdown
[](https://www.npmjs.com/package/eslint-scope)
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[](https://www.npmjs.com/package/eslint-scope)
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[](https://github.com/eslint/eslint-scope/actions)
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# ESLint Scope
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ESLint Scope is the [ECMAScript](http://www.ecma-international.org/publications/standards/Ecma-262.htm) scope analyzer used in ESLint. It is a fork of [escope](http://github.com/estools/escope).
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## Install
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```
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npm i eslint-scope --save
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```
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## 📖 Usage
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To use in an ESM file:
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```js
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import * as eslintScope from 'eslint-scope';
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```
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To use in a CommonJS file:
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```js
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const eslintScope = require('eslint-scope');
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```
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In order to analyze scope, you'll need to have an [ESTree](https://github.com/estree/estree) compliant AST structure to run it on. The primary method is `eslintScope.analyze()`, which takes two arguments:
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1. `ast` - the ESTree-compliant AST structure to analyze.
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2. `options` (optional) - Options to adjust how the scope is analyzed, including:
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* `ignoreEval` (default: `false`) - Set to `true` to ignore all `eval()` calls (which would normally create scopes).
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* `nodejsScope` (default: `false`) - Set to `true` to create a top-level function scope needed for CommonJS evaluation.
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* `impliedStrict` (default: `false`) - Set to `true` to evaluate the code in strict mode even outside of modules and without `"use strict"`.
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* `ecmaVersion` (default: `5`) - The version of ECMAScript to use to evaluate the code.
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* `sourceType` (default: `"script"`) - The type of JavaScript file to evaluate. Change to `"module"` for ECMAScript module code.
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* `childVisitorKeys` (default: `null`) - An object with visitor key information (like [`eslint-visitor-keys`](https://github.com/eslint/eslint-visitor-keys)). Without this, `eslint-scope` finds child nodes to visit algorithmically. Providing this option is a performance enhancement.
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* `fallback` (default: `"iteration"`) - The strategy to use when `childVisitorKeys` is not specified. May be a function.
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Example:
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```js
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import * as eslintScope from 'eslint-scope';
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import * as espree from 'espree';
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import estraverse from 'estraverse';
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const options = {
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ecmaVersion: 2022,
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sourceType: "module"
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};
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const ast = espree.parse(code, { range: true, ...options });
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const scopeManager = eslintScope.analyze(ast, options);
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const currentScope = scopeManager.acquire(ast); // global scope
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estraverse.traverse(ast, {
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enter (node, parent) {
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// do stuff
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if (/Function/.test(node.type)) {
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currentScope = scopeManager.acquire(node); // get current function scope
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}
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},
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leave(node, parent) {
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if (/Function/.test(node.type)) {
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currentScope = currentScope.upper; // set to parent scope
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}
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// do stuff
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}
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});
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```
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## Contributing
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Issues and pull requests will be triaged and responded to as quickly as possible. We operate under the [ESLint Contributor Guidelines](http://eslint.org/docs/developer-guide/contributing), so please be sure to read them before contributing. If you're not sure where to dig in, check out the [issues](https://github.com/eslint/eslint-scope/issues).
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## Security Policy
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We work hard to ensure that ESLint Scope is safe for everyone and that security issues are addressed quickly and responsibly. Read the full [security policy](https://github.com/eslint/.github/blob/master/SECURITY.md).
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## Build Commands
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* `npm test` - run all linting and tests
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* `npm run lint` - run all linting
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## License
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ESLint Scope is licensed under a permissive BSD 2-clause license.
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