hast-util-to-estree
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!Chatchat-badgechathast utility to transform to estree (JSX).
Contents
* [`toEstree(tree[, options])`](#toestreetree-options)
* [`defaultHandlers`](#defaulthandlers)
* [`ElementAttributeNameCase`](#elementattributenamecase)
* [`Handle`](#handle)
* [`Options`](#options)
* [`Space`](#space)
* [`State`](#state)
* [`StylePropertyNameCase`](#stylepropertynamecase)
What is this?
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.When should I use this?
This project is useful when you want to embed HTML as JSX inside JS while working with syntax trees. This is used in MDX.Install
This package is ESM onlyesm. In Node.js (version 16+), install with npm:npm install hast-util-to-estree
In Deno with
esm.sh
esmsh:import {toEstree} from 'https://esm.sh/hast-util-to-estree@3'
In browsers with
esm.sh
esmsh:<script type="module">
import {toEstree} from 'https://esm.sh/hast-util-to-estree@3?bundle'
</script>
Use
Say our moduleexample.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 {jsx, toJs} from 'estree-util-to-js'
import {fromHtml} from 'hast-util-from-html'
import {toEstree} from 'hast-util-to-estree'
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>
</>
API
This package exports the identifiersdefaultHandlers
api-default-handlers
and toEstree
api-to-estree.
There is no default export.toEstree(tree[, options])
Transform a hast tree (with embedded MDX nodes) into an estree (with JSX
nodes).Notes
Comments
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.Frameworks
There are differences between what JSX frameworks accept, such as whether they acceptclass
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'
|Parameters
— hast tree
options
(Options
api-options, optional)
— configuration
Returns
estree program node (Program
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
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
estree-util-to-js.
Or, use estree-util-build-jsx
build-jsx to turn JSX into function
calls, and then serialize with whatever (astring
, escodegen
).defaultHandlers
Default handlers for elements (Record<string, Handle>
).Each key is a node type, each value is a
Handle
api-handle.ElementAttributeNameCase
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
type ElementAttributeNameCase = 'html' | 'react'
Handle
Turn a hast node into an estree node (TypeScript type).Parameters
— expected hast node
— info passed around about the current state
Returns
JSX child (JsxChild
, optional).You can also add more results to
state.esm
and state.comments
.Options
Configuration (TypeScript type).Fields
elementAttributeNameCase
([`ElementAttributeNameCase`][api-element-attribute-name-case], 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 handlers
— 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 it
stylePropertyNameCase
([`StylePropertyNameCase`][api-style-property-name-case],
default: `'dom'`)
— specify casing to use for property names in `style` objects; this casing
is used for hast elements, not for embedded MDX JSX nodes (components that
someone authored manually)
tableCellAlignToStyle
(boolean
, default:true
)
— turn obsolete `align` props on `td` and `th` into CSS `style` props
Space
Namespace (TypeScript type).Type
type Space = 'html' | 'svg'
State
Info passed around about the current state (TypeScript type).Fields
all
((node: HastParent) => EstreeJsxChild | undefined
)
— transform children of a hast parent to estree
comments
(Array<EstreeComment>
)
— list of estree comments
createJsxAttributeName
((name: string) => EstreeJsxAttributeName
)
— create a JSX attribute name
createJsxElementName
((name: string) => EstreeJsxElementName
)
— create a JSX attribute name
elementAttributeNameCase
([`ElementAttributeNameCase`][api-element-attribute-name-case])
— casing to use for attribute names
esm
(Array<EstreeNode>
)
— list of top-level estree nodes
handle
((node: HastNode) => EstreeJsxChild | undefined
)
— transform a hast node to estree
inherit
((from: HastNode, to: EstreeNode) => undefined
)
— take positional info and data from `from` (use `patch` if you don’t want
data)
patch
((from: HastNode, to: EstreeNode) => undefined
)
— take positional info from `from` (use `inherit` if you also want data)
— current schema
stylePropertyNameCase
([`StylePropertyNameCase`][api-style-property-name-case])
— casing for property names in `style` objects
tableCellAlignToStyle
(boolean
)
— turn obsolete `align` props on `td` and `th` into CSS `style` props
StylePropertyNameCase
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
type StylePropertyNameCase = 'css' | 'dom'
Types
This package is fully typed with TypeScript. It exports the additional typesElementAttributeNameCase
api-element-attribute-name-case,
Handle
api-handle, Options
api-options,
Space
api-space, State
api-state, and
StylePropertyNameCase
api-style-property-name-case.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,
hast-util-to-estree@^3
,
compatible with Node.js 16.Security
You’re working with JavaScript. It’s not safe.Related
— transform JSX to function calls
— hyperscript compatible interface for creating nodes
— transform a DOM tree to hast
Contribute
Seecontributing.md
contributing in syntax-tree/.github
health for
ways to get started.
See support.md
support for ways to get help.This project has a code of conductcoc. By interacting with this repository, organization, or community you agree to abide by its terms.