hast-util-to-estree

hast utility to transform a tree to estree JSX.

Install

This package is ESM only: Node 12+ is needed to use it and it must be imported instead of required.

npm install hast-util-to-estree

Use

Say we have the following HTML file, example.html:

<!doctype html>
<html lang=en>
<title>Hi!</title>
<link rel=stylesheet href=index.css>
<h1>Hello, world!</h1>
<a download style="width:1;height:10px"></a>
<!--commentz-->
<svg xmlns="http://www.w3.org/2000/svg">
  <title>SVG `&lt;ellipse&gt;` element</title>
  <ellipse
    cx="120"
    cy="70"
    rx="100"
    ry="50"
  />
</svg>
<script src="index.js"></script>

And our script, example.js, is:

import fs from 'node:fs'
import parse5 from 'parse5'
import {fromParse5} from 'hast-util-from-parse5'
import {toEstree} from 'hast-util-to-estree'
import recast from 'recast'

const hast = fromParse5(parse5.parse(String(fs.readFileSync('example.html'))))

const estree = toEstree(hast)

estree.comments = null // `recast` doesn’t like comments on the root.
console.log(recast.prettyPrint(estree).code)

Now, node example (and prettier), yields:

;<>
  <html lang="en">
    <head>
      <title>{'Hi!'}</title>
      {'\n'}
      <link rel="stylesheet" href="index.css" />
      {'\n'}
    </head>
    <body>
      <h1>{'Hello, world!'}</h1>
      {'\n'}
      <a
        download
        style={{
          width: '1',
          height: '10px'
        }}
      />
      {'\n'}
      {/*commentz*/}
      {'\n'}
      <svg xmlns="http://www.w3.org/2000/svg">
        {'\n  '}
        <title>{'SVG `<ellipse>` element'}</title>
        {'\n  '}
        <ellipse cx="120" cy="70" rx="100" ry="50" />
        {'\n'}
      </svg>
      {'\n'}
      <script src="index.js" />
      {'\n'}
    </body>
  </html>
</>

API

This package exports the following identifiers: toEstree. There is no default export.

`toEstree(tree, options?)`

Transform a hast tree to an estree (JSX).

`options`

space (enum, 'svg' or 'html', default: 'html') — Whether node is in the 'html' or 'svg' space. If an svg element is found when inside the HTML space, toEstree automatically switches to the SVG space when entering the element, and switches back when exiting

Returns

estree — a Program node, whose last child in body is most likely an ExpressionStatement whose expression is a JSXFragment or a JSXElement.

Typically, there is only one node in body, however, this utility also supports embedded MDX nodes in the HTML (when mdast-util-mdx is used with mdast to parse markdown before passing its nodes through to hast). When MDX ESM import/exports are used, those nodes are added before the fragment or element in body.

Note

Comments are both attached to the tree in their neighbouring nodes (recast and babel style), and added as a comments array on the program node (espree style). You may have to do program.comments = null for certain compilers.

There aren’t many great estree serializers out there that support JSX. recast does a fine job. Or use estree-util-build-jsx to turn JSX into function calls and then serialize with whatever (astring, escodegen).

Security

You’re working with JavaScript. It’s not safe.

hastscript — Hyperscript compatible interface for creating nodes
hast-util-from-dom — Transform a DOM tree to hast
unist-builder — Create any unist tree
xastscript — Create a xast tree
estree-util-build-jsx — Transform JSX to function calls

Contribute

See contributing.md in syntax-tree/.github for ways to get started. See support.md for ways to get help.

This project has a code of conduct. By interacting with this repository, organization, or community you agree to abide by its terms.

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