eslint-visitor-keys


Constants and utilities about visitor keys to traverse AST.

💿 Installation

Use [npm] to install.

``bash
$ npm install eslint-visitor-keys
`

$3

- [Node.js] ^20.19.0, ^22.13.0, or >=24

📖 Usage

To use in an ESM file:

`js
import * as evk from "eslint-visitor-keys"
`

To use in a CommonJS file:

`js
const evk = require("eslint-visitor-keys")
`

$3

> type: { [type: string]: string[] | undefined }

Visitor keys. This keys are frozen.

This is an object. Keys are the type of [ESTree] nodes. Their values are an array of property names which have child nodes.

For example:

`
console.log(evk.KEYS.AssignmentExpression) // → ["left", "right"]
`

$3

> type: (node: object) => string[]

Get the visitor keys of a given AST node.

This is similar to Object.keys(node) of ES Standard, but some keys are excluded: parent, leadingComments, trailingComments, and names which start with _.

This will be used to traverse unknown nodes.

For example:

`js
const node = {
type: "AssignmentExpression",
left: { type: "Identifier", name: "foo" },
right: { type: "Literal", value: 0 }
}
console.log(evk.getKeys(node)) // → ["type", "left", "right"]
`

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> type: (additionalKeys: object) => { [type: string]: string[] | undefined }

Make the union set with evk.KEYS and the given keys.

- The order of keys is, additionalKeys is at first, then evk.KEYS is concatenated after that.
- It removes duplicated keys as keeping the first one.

For example:

`js
console.log(evk.unionWith({
MethodDefinition: ["decorators"]
})) // → { ..., MethodDefinition: ["decorators", "key", "value"], ... }
`

📰 Change log

See GitHub releases.

🍻 Contributing

Welcome. See ESLint contribution guidelines.

$3

- npm test runs tests and measures code coverage.
- npm run lint checks source codes with ESLint.
- npm run test:open-coverage` opens the code coverage report of the previous test with your default browser.

[npm]: https://www.npmjs.com/
[Node.js]: https://nodejs.org/
[ESTree]: https://github.com/estree/estree

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