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https://github.com/jsx-eslint/jsx-ast-utils

AST utility module for statically analyzing JSX
https://github.com/jsx-eslint/jsx-ast-utils

ast ast-parser eslint jsx utility

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AST utility module for statically analyzing JSX

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# jsx-ast-utils [![Version Badge][npm-version-svg]][package-url]



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[![npm badge][npm-badge-png]][package-url]



AST utility module for statically analyzing JSX.



## Installation

```sh

$ npm i jsx-ast-utils --save

```



## Usage

This is a utility module to evaluate AST objects for JSX syntax. This can be super useful when writing linting rules for JSX code. It was originally in the code for [eslint-plugin-jsx-a11y](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y), however I thought it could be useful to be extracted and maintained separately so **you** could write new interesting rules to statically analyze JSX.



### ESLint example

```js

import { hasProp } from 'jsx-ast-utils';

// OR: var hasProp = require('jsx-ast-utils').hasProp;

// OR: const hasProp = require('jsx-ast-utils/hasProp');

// OR: import hasProp from 'jsx-ast-utils/hasProp';



module.exports = context => ({

  JSXOpeningElement: node => {

    const onChange = hasProp(node.attributes, 'onChange');



    if (onChange) {

      context.report({

        node,

        message: `No onChange!`

      });

    }

  }

});

```



## API

### AST Resources

1. [JSX spec](https://github.com/facebook/jsx/blob/master/AST.md)

2. [JS spec](https://github.com/estree/estree/blob/master/spec.md)



### hasProp

```js

hasProp(props, prop, options);

```

Returns boolean indicating whether an prop exists as an attribute on a JSX element node.



#### Props

Object - The attributes on the visited node. (Usually `node.attributes`).

#### Prop

String - A string representation of the prop you want to check for existence.

#### Options

Object - An object representing options for existence checking

  1. `ignoreCase` - automatically set to `true`.

  2. `spreadStrict` - automatically set to `true`. This means if spread operator exists in

     props, it will assume the prop you are looking for is not in the spread.

     Example: `
` looking for specific prop here will return false if `spreadStrict` is `true`.






### hasAnyProp



```js

hasAnyProp(props, prop, options);

```

Returns a boolean indicating if **any** of props in `prop` argument exist on the node.



#### Props

Object - The attributes on the visited node. (Usually `node.attributes`).

#### Prop

Array - An array of strings representing the props you want to check for existence.

#### Options

Object - An object representing options for existence checking

  1. `ignoreCase` - automatically set to `true`.

  2. `spreadStrict` - automatically set to `true`. This means if spread operator exists in

     props, it will assume the prop you are looking for is not in the spread.

     Example: `
` looking for specific prop here will return false if `spreadStrict` is `true`.






### hasEveryProp



```js

hasEveryProp(props, prop, options);

```

Returns a boolean indicating if **all** of props in `prop` argument exist on the node.



#### Props

Object - The attributes on the visited node. (Usually `node.attributes`).

#### Prop

Array - An array of strings representing the props you want to check for existence.

#### Options

Object - An object representing options for existence checking

 1. `ignoreCase` - automatically set to `true`.

 2. `spreadStrict` - automatically set to `true`. This means if spread operator exists in

    props, it will assume the prop you are looking for is not in the spread.

    Example: `
` looking for specific prop here will return false if `spreadStrict` is `true`.






### getProp



```js

getProp(props, prop, options);

```

Returns the JSXAttribute itself or undefined, indicating the prop is not present on the JSXOpeningElement.



#### Props

Object - The attributes on the visited node. (Usually `node.attributes`).

#### Prop

String - A string representation of the prop you want to check for existence.

#### Options

Object - An object representing options for existence checking

  1. `ignoreCase` - automatically set to `true`.






### elementType

```js

elementType(node)

```

Returns the tagName associated with a JSXElement.



#### Node

Object - The visited JSXElement node object.






### getPropValue



```js

getPropValue(prop);

```

Returns the value of a given attribute. Different types of attributes have their associated values in different properties on the object.



This function should return the most *closely* associated value with the intention of the JSX.



#### Prop

Object - The JSXAttribute collected by AST parser.






### getLiteralPropValue



```js

getLiteralPropValue(prop);

```

Returns the value of a given attribute. Different types of attributes have their associated values in different properties on the object.



This function should return a value only if we can extract a literal value from its attribute (i.e. values that have generic types in JavaScript - strings, numbers, booleans, etc.)



#### Prop

Object - The JSXAttribute collected by AST parser.






### propName



```js

propName(prop);

```

Returns the name associated with a JSXAttribute. For example, given `
` and the JSXAttribute for `foo`, this will return the string `"foo"`.



#### Prop

Object - The JSXAttribute collected by AST parser.






### eventHandlers



```js

console.log(eventHandlers);

/*

[

  'onCopy',

  'onCut',

  'onPaste',

  'onCompositionEnd',

  'onCompositionStart',

  'onCompositionUpdate',

  'onKeyDown',

  'onKeyPress',

  'onKeyUp',

  'onFocus',

  'onBlur',

  'onChange',

  'onInput',

  'onSubmit',

  'onClick',

  'onContextMenu',

  'onDblClick',

  'onDoubleClick',

  'onDrag',

  'onDragEnd',

  'onDragEnter',

  'onDragExit',

  'onDragLeave',

  'onDragOver',

  'onDragStart',

  'onDrop',

  'onMouseDown',

  'onMouseEnter',

  'onMouseLeave',

  'onMouseMove',

  'onMouseOut',

  'onMouseOver',

  'onMouseUp',

  'onSelect',

  'onTouchCancel',

  'onTouchEnd',

  'onTouchMove',

  'onTouchStart',

  'onScroll',

  'onWheel',

  'onAbort',

  'onCanPlay',

  'onCanPlayThrough',

  'onDurationChange',

  'onEmptied',

  'onEncrypted',

  'onEnded',

  'onError',

  'onLoadedData',

  'onLoadedMetadata',

  'onLoadStart',

  'onPause',

  'onPlay',

  'onPlaying',

  'onProgress',

  'onRateChange',

  'onSeeked',

  'onSeeking',

  'onStalled',

  'onSuspend',

  'onTimeUpdate',

  'onVolumeChange',

  'onWaiting',

  'onLoad',

  'onError',

  'onAnimationStart',

  'onAnimationEnd',

  'onAnimationIteration',

  'onTransitionEnd',

]

*/

```



Contains a flat list of common event handler props used in JSX to attach behaviors

to DOM events.



#### eventHandlersByType



The same list as `eventHandlers`, grouped into types.



```js

console.log(eventHandlersByType);

/*

{

  clipboard: [ 'onCopy', 'onCut', 'onPaste' ],

  composition: [ 'onCompositionEnd', 'onCompositionStart', 'onCompositionUpdate' ],

  keyboard: [ 'onKeyDown', 'onKeyPress', 'onKeyUp' ],

  focus: [ 'onFocus', 'onBlur' ],

  form: [ 'onChange', 'onInput', 'onSubmit' ],

  mouse: [ 'onClick', 'onContextMenu', 'onDblClick', 'onDoubleClick', 'onDrag', 'onDragEnd', 'onDragEnter', 'onDragExit', 'onDragLeave', 'onDragOver', 'onDragStart', 'onDrop', 'onMouseDown', 'onMouseEnter', 'onMouseLeave', 'onMouseMove', 'onMouseOut', 'onMouseOver', 'onMouseUp' ],

  selection: [ 'onSelect' ],

  touch: [ 'onTouchCancel', 'onTouchEnd', 'onTouchMove', 'onTouchStart' ],

  ui: [ 'onScroll' ],

  wheel: [ 'onWheel' ],

  media: [ 'onAbort', 'onCanPlay', 'onCanPlayThrough', 'onDurationChange', 'onEmptied', 'onEncrypted', 'onEnded', 'onError', 'onLoadedData', 'onLoadedMetadata', 'onLoadStart', 'onPause', 'onPlay', 'onPlaying', 'onProgress', 'onRateChange', 'onSeeked', 'onSeeking', 'onStalled', 'onSuspend', 'onTimeUpdate', 'onVolumeChange', 'onWaiting' ],

  image: [ 'onLoad', 'onError' ],

  animation: [ 'onAnimationStart', 'onAnimationEnd', 'onAnimationIteration' ],

  transition: [ 'onTransitionEnd' ],

}

*/

```



[1]: https://npmjs.org/package/jsx-ast-utils

[2]: https://versionbadg.es/jsx-eslint/jsx-ast-utils.svg

[5]: https://david-dm.org/jsx-eslint/jsx-ast-utils.svg

[6]: https://david-dm.org/jsx-eslint/jsx-ast-utils

[7]: https://david-dm.org/jsx-eslint/jsx-ast-utils/dev-status.svg

[8]: https://david-dm.org/jsx-eslint/jsx-ast-utils#info=devDependencies

[11]: https://nodei.co/npm/jsx-ast-utils.png?downloads=true&stars=true

[license-image]: https://img.shields.io/npm/l/jsx-ast-utils.svg

[license-url]: LICENSE

[downloads-image]: https://img.shields.io/npm/dm/jsx-ast-utils.svg

[downloads-url]: https://npm-stat.com/charts.html?package=jsx-ast-utils

[codecov-image]: https://codecov.io/gh/jsx-eslint/jsx-ast-utils/branch/main/graphs/badge.svg

[codecov-url]: https://app.codecov.io/gh/jsx-eslint/jsx-ast-utils/

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