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https://github.com/syntax-tree/estree-util-build-jsx

Transform JSX in estrees to function calls (for react, preact, and most hyperscript interfaces)
https://github.com/syntax-tree/estree-util-build-jsx

ecmascript estree hyperscript javascript jsx preact react

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Transform JSX in estrees to function calls (for react, preact, and most hyperscript interfaces)

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# estree-util-build-jsx



[![Build][build-badge]][build]

[![Coverage][coverage-badge]][coverage]

[![Downloads][downloads-badge]][downloads]

[![Size][size-badge]][size]

[![Sponsors][sponsors-badge]][collective]

[![Backers][backers-badge]][collective]

[![Chat][chat-badge]][chat]



[estree][] utility to turn JSX into function calls: `` -> `h('x')`!



## Contents



*   [What is this?](#what-is-this)

*   [When should I use this?](#when-should-i-use-this)

*   [Install](#install)

*   [Use](#use)

*   [API](#api)

    *   [`buildJsx(tree[, options])`](#buildjsxtree-options)

    *   [`Options`](#options)

    *   [`Runtime`](#runtime-1)

*   [Examples](#examples)

    *   [Example: use with Acorn](#example-use-with-acorn)

*   [Types](#types)

*   [Compatibility](#compatibility)

*   [Related](#related)

*   [Security](#security)

*   [Contribute](#contribute)

*   [License](#license)



## What is this?



This package is a utility that takes an [estree][] (JavaScript) syntax tree as

input that contains embedded JSX nodes (elements, fragments) and turns them into

function calls.



## When should I use this?



If you already have a tree and only need to compile JSX away, use this.

If you have code, use something like [SWC][] or [esbuild][] instead.



## Install



This package is [ESM only][esm].

In Node.js (version 16+), install with [npm][]:



```sh

npm install estree-util-build-jsx

```



In Deno with [`esm.sh`][esmsh]:



```js

import {buildJsx} from 'https://esm.sh/estree-util-build-jsx@3'

```



In browsers with [`esm.sh`][esmsh]:



```html



  import {buildJsx} from 'https://esm.sh/estree-util-build-jsx@3?bundle'



```



## Use



Say we have the following `example.jsx`:



```js

import x from 'xastscript'



console.log(

  

    Born in the U.S.A.

    Bruce Springsteen

    April 6, 1984

  

)



console.log(

  <>

    {1 + 1}

    

    

  >

)

```



…and next to it a module `example.js`:



```js

import fs from 'node:fs/promises'

import jsx from 'acorn-jsx'

import {fromJs} from 'esast-util-from-js'

import {buildJsx} from 'estree-util-build-jsx'

import {toJs} from 'estree-util-to-js'



const doc = String(await fs.readFile('example.jsx'))



const tree = fromJs(doc, {module: true, plugins: [jsx()]})



buildJsx(tree, {pragma: 'x', pragmaFrag: 'null'})



console.log(toJs(tree).value)

```



…now running `node example.js` yields:



```js

import x from "xastscript";

console.log(x("album", {

  id: 123

}, x("name", null, "Born in the U.S.A."), x("artist", null, "Bruce Springsteen"), x("releasedate", {

  date: "1984-04-06"

}, "April 6, 1984")));

console.log(x(null, null, 1 + 1, x("self-closing"), x("x", Object.assign({

  name: true,

  key: "value",

  key: expression

}, spread))));

```



## API



This package exports the identifier [`buildJsx`][api-build-jsx].

There is no default export.



### `buildJsx(tree[, options])`



Turn JSX in `tree` into function calls: `` -> `h('x')`!



###### Algorithm



In almost all cases, this utility is the same as the Babel plugin, except that

they work on slightly different syntax trees.



Some differences:



*   no pure annotations things

*   `this` is not a component: `` -> `h('this')`, not `h(this)`

*   namespaces are supported: `` -> `h('a:b', {'c:d': true})`,

    which throws by default in Babel or can be turned on with `throwIfNamespace`

*   no `useSpread`, `useBuiltIns`, or `filter` options



###### Parameters



*   `tree` ([`Node`][node])

    — tree to transform (typically [`Program`][program])

*   `options` ([`Options`][api-options], optional)

    — configuration



###### Returns



Nothing (`undefined`).



### `Options`



Configuration (TypeScript type).



> 👉 **Note**: you can also configure `runtime`, `importSource`, `pragma`, and

> `pragmaFrag` from within files through comments.



##### Fields



###### `runtime`



Choose the [runtime][jsx-runtime] ([`Runtime`][api-runtime], default: `'classic'`).



Comment form: `@jsxRuntime theRuntime`.



###### `importSource`



Place to import `jsx`, `jsxs`, `jsxDEV`, and `Fragment` from, when the

effective runtime is automatic (`string`, default: `'react'`).



Comment form: `@jsxImportSource theSource`.



> 👉 **Note**: `/jsx-runtime` or `/jsx-dev-runtime` is appended to this provided

> source.

> In CJS, that can resolve to a file (as in `theSource/jsx-runtime.js`), but for

> ESM an export map needs to be set up to point to files:

>

> ```js

> // …

> "exports": {

>   // …

>   "./jsx-runtime": "./path/to/jsx-runtime.js",

>   "./jsx-dev-runtime": "./path/to/jsx-runtime.js"

>   // …

> ```



###### `pragma`



Identifier or member expression to call when the effective runtime is classic

(`string`, default: `'React.createElement'`).



Comment form: `@jsx identifier`.



###### `pragmaFrag`



Identifier or member expression to use as a symbol for fragments when the

effective runtime is classic (`string`, default: `'React.Fragment'`).



Comment form: `@jsxFrag identifier`.



###### `development`



When in the automatic runtime, whether to import `theSource/jsx-dev-runtime.js`,

use `jsxDEV`, and pass location info when available (`boolean`, default: `false`).



This helps debugging but adds a lot of code that you don’t want in production.



###### `filePath`



File path to the original source file (`string`, example: `'path/to/file.js'`).

Passed in location info to `jsxDEV` when using the automatic runtime with

`development: true`.



### `Runtime`



How to transform JSX (TypeScript type).



###### Type



```ts

type Runtime = 'automatic' | 'classic'

```



## Examples



### Example: use with Acorn



To support configuration from comments in Acorn, those comments have to be in

the program.

This is done by [`espree`][espree] but not automatically by [`acorn`][acorn]:



```js

import {Parser} from 'acorn'

import jsx from 'acorn-jsx'



const doc = '' // To do: get `doc` somehow.



const comments = []

const tree = Parser.extend(jsx()).parse(doc, {onComment: comments})

tree.comments = comments

```



## Types



This package is fully typed with [TypeScript][].

It exports the additional type [`Options`][api-options] and

[`Runtime`][api-runtime].



## Compatibility



Projects maintained by the unified collective are compatible with maintained

versions of Node.js.



When we cut a new major release, we drop support for unmaintained versions of

Node.

This means we try to keep the current release line, `estree-util-build-jsx@^3`,

compatible with Node.js 166.



## Related



*   [`syntax-tree/hast-util-to-estree`](https://github.com/syntax-tree/hast-util-to-estree)

    — turn [hast](https://github.com/syntax-tree/hast) (HTML) to [estree][]

    JSX

*   [`coderaiser/estree-to-babel`](https://github.com/coderaiser/estree-to-babel)

    — turn [estree][] to Babel trees



## Security



This package is safe.



## Contribute



See [`contributing.md` in `syntax-tree/.github`][contributing] for ways to get

started.

See [`support.md`][support] for ways to get help.



This project has a [code of conduct][coc].

By interacting with this repository, organization, or community you agree to

abide by its terms.



## License



[MIT][license] © [Titus Wormer][author]



[build-badge]: https://github.com/syntax-tree/estree-util-build-jsx/workflows/main/badge.svg



[build]: https://github.com/syntax-tree/estree-util-build-jsx/actions



[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/estree-util-build-jsx.svg



[coverage]: https://codecov.io/github/syntax-tree/estree-util-build-jsx



[downloads-badge]: https://img.shields.io/npm/dm/estree-util-build-jsx.svg



[downloads]: https://www.npmjs.com/package/estree-util-build-jsx



[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=estree-util-build-jsx



[size]: https://bundlejs.com/?q=estree-util-build-jsx



[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg



[backers-badge]: https://opencollective.com/unified/backers/badge.svg



[collective]: https://opencollective.com/unified



[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg



[chat]: https://github.com/syntax-tree/unist/discussions



[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c



[npm]: https://docs.npmjs.com/cli/install



[esmsh]: https://esm.sh



[license]: license



[author]: https://wooorm.com



[typescript]: https://www.typescriptlang.org



[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md



[support]: https://github.com/syntax-tree/.github/blob/main/support.md



[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md



[acorn]: https://github.com/acornjs/acorn



[estree]: https://github.com/estree/estree



[espree]: https://github.com/eslint/espree



[node]: https://github.com/estree/estree/blob/master/es5.md#node-objects



[program]: https://github.com/estree/estree/blob/master/es5.md#programs



[jsx-runtime]: https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html



[swc]: https://swc.rs



[esbuild]: https://esbuild.github.io



[api-build-jsx]: #buildjsxtree-options



[api-options]: #options



[api-runtime]: #runtime-1