hast utility to transform to estree (JSX).
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This package is a utility that takes a hast (HTML) syntax tree as input and turns it into an estree (JavaScript) syntax tree (with a JSX extension). This package also supports embedded MDX nodes.
This project is useful when you want to embed HTML as JSX inside JS while working with syntax trees. This is used in MDX.
This package is ESM only. In Node.js (version 14.14+ and 16.0+), install with npm:
npm install hast-util-to-estreeIn Deno with esm.sh:
import {toEstree} from 'https://esm.sh/hast-util-to-estree@2'In browsers with esm.sh:
<script type="module">
import {toEstree} from 'https://esm.sh/hast-util-to-estree@2?bundle'
</script>Say our module example.html contains:
<!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 `<ellipse>` element</title>
<ellipse
cx="120"
cy="70"
rx="100"
ry="50"
/>
</svg>
<script src="index.js"></script>…and our module example.js looks as follows:
import fs from 'node:fs/promises'
import {fromHtml} from 'hast-util-from-html'
import {toEstree} from 'hast-util-to-estree'
import {toJs, jsx} from 'estree-util-to-js'
const hast = fromHtml(await fs.readFile('example.html'))
const estree = toEstree(hast)
console.log(toJs(estree, {handlers: jsx}).value)…now running node example.js (and prettier) yields:
/* Commentz */
;<>
<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'}
{}
{'\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>
</>This package exports the identifiers defaultHandlers
and toEstree.
There is no default export.
Transform a hast tree (with embedded MDX nodes) into an estree (with JSX nodes).
Comments are attached to the tree in their neighbouring nodes (recast,
babel style) and also added as a comments array on the program node
(espree style).
You may have to do program.comments = undefined for certain compilers.
There are differences between what JSX frameworks accept, such as whether they
accept class or className, or background-color or backgroundColor.
For JSX components written in MDX, the author has to be aware of this difference and write code accordingly. For hast elements transformed by this project, this will be handled through options.
| Framework | elementAttributeNameCase |
stylePropertyNameCase |
|---|---|---|
| Preact | 'html' |
'dom' |
| React | 'react' |
'dom' |
| Solid | 'html' |
'css' |
| Vue | 'html' |
'dom' |
estree program node (Program).
The program’s 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.
There aren’t many great estree serializers out there that support JSX.
To do that, you can use estree-util-to-js.
Or, use estree-util-build-jsx to turn JSX into function
calls, and then serialize with whatever (astring, escodegen).
Default handlers for elements (Record<string, Handle>).
Each key is a node type, each value is a Handle.
Specify casing to use for attribute names (TypeScript type).
HTML casing is for example class, stroke-linecap, xml:lang.
React casing is for example className, strokeLinecap, xmlLang.
type ElementAttributeNameCase = 'html' | 'react'Turn a hast node into an estree node (TypeScript type).
JSX child (JsxChild, optional).
You can also add more results to state.esm and state.comments.
Configuration (TypeScript type).
elementAttributeNameCase(ElementAttributeNameCase, default:'react') — specify casing to use for attribute names; this casing is used for hast elements, not for embedded MDX JSX nodes (components that someone authored manually)handlers(Record<string, Handle>, optional) — custom handlersspace(Space, default:'html'). which space the document is in; when an<svg>element is found in the HTML space, this package already automatically switches to and from the SVG space when entering and exiting itstylePropertyNameCase(StylePropertyNameCase, default:'dom') — specify casing to use for property names instyleobjects; this casing is used for hast elements, not for embedded MDX JSX nodes (components that someone authored manually)
Namespace (TypeScript type).
type Space = 'html' | 'svg'Info passed around about the current state (TypeScript type).
schema(Schema) — current schemaelementAttributeNameCase(ElementAttributeNameCase) — casing to use for attribute namescomments(Array<EstreeComment>) — list of estree commentsesm(Array<EstreeNode>) — list of top-level estree nodeshandle((node: HastNode) => EstreeJsxChild | void) — transform a hast node to estreehandle((node: HastParent) => EstreeJsxChild | void) — transform children of a hast parent to estreepatch((from: HastNode, to: EstreeNode) => void) — take positional info fromfrom(useinheritif you also want data)inherit((from: HastNode, to: EstreeNode) => void) — take positional info and data fromfrom(usepatchif you don’t want data)createJsxAttributeName((name: string) => EstreeJsxAttributeName) — create a JSX attribute namecreateJsxElementName((name: string) => EstreeJsxElementName) — create a JSX attribute name
Casing to use for property names in style objects (TypeScript type).
CSS casing is for example background-color and -webkit-line-clamp.
DOM casing is for example backgroundColor and WebkitLineClamp.
type StylePropertyNameCase = 'dom' | 'css'This package is fully typed with TypeScript.
It exports the additional types
ElementAttributeNameCase,
Handle, Options,
Space, State, and
StylePropertyNameCase.
Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 14.14+ and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.
You’re working with JavaScript. It’s not safe.
hastscript— hyperscript compatible interface for creating nodeshast-util-from-dom— transform a DOM tree to hastestree-util-build-jsx— transform JSX to function calls
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.
