https://github.com/syntax-tree/hastscript
utility to create hast trees
https://github.com/syntax-tree/hastscript
hast hast-util html hyperscript unist util
Last synced: about 1 month ago
JSON representation
utility to create hast trees
- Host: GitHub
- URL: https://github.com/syntax-tree/hastscript
- Owner: syntax-tree
- License: mit
- Created: 2016-02-24T19:07:56.000Z (over 9 years ago)
- Default Branch: main
- Last Pushed: 2025-02-19T13:17:58.000Z (4 months ago)
- Last Synced: 2025-04-29T06:02:24.293Z (about 2 months ago)
- Topics: hast, hast-util, html, hyperscript, unist, util
- Language: JavaScript
- Homepage: https://unifiedjs.com
- Size: 232 KB
- Stars: 178
- Watchers: 10
- Forks: 13
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
- License: license
Awesome Lists containing this project
- awesome-syntax-tree - hastscript - Create trees with a nice syntax. (hast utilities)
README
# hastscript
[![Build][badge-build-image]][badge-build-url]
[![Coverage][badge-coverage-image]][badge-coverage-url]
[![Downloads][badge-downloads-image]][badge-downloads-url]
[![Size][badge-size-image]][badge-size-url]
[hast][github-hast] utility to create trees with ease.
## Contents
* [What is this?](#what-is-this)
* [When should I use this?](#when-should-i-use-this)
* [Install](#install)
* [Use](#use)
* [API](#api)
* [`h(selector?[, properties][, …children])`](#hselector-properties-children)
* [`s(selector?[, properties][, …children])`](#sselector-properties-children)
* [`Child`](#child)
* [`Properties`](#properties-1)
* [`Result`](#result)
* [Syntax tree](#syntax-tree)
* [JSX](#jsx)
* [Compatibility](#compatibility)
* [Security](#security)
* [Related](#related)
* [Contribute](#contribute)
* [License](#license)
## What is this?
This package is a hyperscript interface (like `createElement` from React and
`h` from Vue and such) to help with creating hast trees.
## When should I use this?
You can use this utility in your project when you generate hast syntax trees
with code.
It helps because it replaces most of the repetition otherwise needed in a syntax
tree with function calls.
It also helps as it improves the attributes you pass by turning them into the
form that is required by hast.
You can instead use [`unist-builder`][github-unist-builder]
when creating any unist nodes and
[`xastscript`][github-xastscript] when creating xast (XML) nodes.
## Install
This package is [ESM only][github-gist-esm].
In Node.js (version 16+),
install with [npm][npmjs-install]:
```sh
npm install hastscript
```
In Deno with [`esm.sh`][esmsh]:
```js
import {h} from 'https://esm.sh/hastscript@9'
```
In browsers with [`esm.sh`][esmsh]:
```html
import {h} from 'https://esm.sh/hastscript@9?bundle'
```
## Use
```js
import {h, s} from 'hastscript'
console.log(
h('.foo#some-id', [
h('span', 'some text'),
h('input', {type: 'text', value: 'foo'}),
h('a.alpha', {class: 'bravo charlie', download: 'download'}, [
'delta',
'echo'
])
])
)
console.log(
s('svg', {viewbox: '0 0 500 500', xmlns: 'http://www.w3.org/2000/svg'}, [
s('title', 'SVG `` element'),
s('circle', {cx: 120, cy: 120, r: 100})
])
)
```
Yields:
```js
{
type: 'element',
tagName: 'div',
properties: {className: ['foo'], id: 'some-id'},
children: [
{
type: 'element',
tagName: 'span',
properties: {},
children: [{type: 'text', value: 'some text'}]
},
{
type: 'element',
tagName: 'input',
properties: {type: 'text', value: 'foo'},
children: []
},
{
type: 'element',
tagName: 'a',
properties: {className: ['alpha', 'bravo', 'charlie'], download: true},
children: [{type: 'text', value: 'delta'}, {type: 'text', value: 'echo'}]
}
]
}
{
type: 'element',
tagName: 'svg',
properties: {viewBox: '0 0 500 500', xmlns: 'http://www.w3.org/2000/svg'},
children: [
{
type: 'element',
tagName: 'title',
properties: {},
children: [{type: 'text', value: 'SVG `` element'}]
},
{
type: 'element',
tagName: 'circle',
properties: {cx: 120, cy: 120, r: 100},
children: []
}
]
}
```
## API
This package exports the identifiers [`h`][api-h] and [`s`][api-s].
There is no default export.
It exports the additional [TypeScript][] types
[`Child`][api-child],
[`Properties`][api-properties],
and
[`Result`][api-result].
The export map supports the automatic JSX runtime.
You can pass `hastscript` or `hastscript/svg` to your build tool
(TypeScript, Babel, SWC)
with an `importSource` option or similar.
### `h(selector?[, properties][, …children])`
Create virtual **[hast][github-hast]** trees for HTML.
##### Signatures
* `h(): root`
* `h(null[, …children]): root`
* `h(selector[, properties][, …children]): element`
##### Parameters
###### `selector`
Simple CSS selector
(`string`, optional).
When string, builds an [`Element`][github-hast-element].
When nullish, builds a [`Root`][github-hast-root] instead.
The selector can contain a tag name (`foo`),
IDs (`#bar`),
and classes (`.baz`).
If the selector is a string but there is no tag name in it then `h` defaults to
build a `div` element and `s` to a `g` element.
`selector` is parsed by
[`hast-util-parse-selector`][github-hast-util-parse-selector].
###### `properties`
Properties of the element
([`Properties`][api-properties], optional).
###### `children`
Children of the node ([`Child`][api-child] or `Array`, optional).
##### Returns
Created tree ([`Result`][api-result]).
[`Element`][github-hast-element] when a `selector` is passed,
otherwise [`Root`][github-hast-root].
### `s(selector?[, properties][, …children])`
Create virtual **[hast][github-hast]** trees for SVG.
Signatures, parameters, and return value are the same as `h` above.
Importantly,
the `selector` and `properties` parameters are interpreted as SVG.
### `Child`
(Lists of) children (TypeScript type).
When strings or numbers are encountered,
they are turned into [`Text`][github-hast-text]
nodes.
[`Root`][github-hast-root] nodes are treated as “fragments”,
meaning that their children are used instead.
###### Type
```ts
type Child =
| Array
| Node
| number
| string
| null
| undefined
```
### `Properties`
Map of properties (TypeScript type).
Keys should match either the HTML attribute name or the DOM property name,
but are case-insensitive.
###### Type
```ts
type Properties = Record<
string,
| boolean
| number
| string
| null
| undefined
// For comma- and space-separated values such as `className`:
| Array
// Accepts value for `style` prop as object.
| Record
>
```
### `Result`
Result from a `h` (or `s`) call (TypeScript type).
###### Type
```ts
type Result = Element | Root
```
## Syntax tree
The syntax tree is [hast][github-hast].
## JSX
This package can be used with JSX.
You should use the automatic JSX runtime set to `hastscript` or
`hastscript/svg`.
> 👉 **Note**
> while `h` supports dots (`.`) for classes or number signs (`#`)
> for IDs in `selector`,
> those are not supported in JSX.
> 🪦 **Legacy**:
> you can also use the classic JSX runtime,
> but this is not recommended.
> To do so,
> import `h` (or `s`) yourself and define it as the pragma
> (plus set the fragment to `null`).
The Use example above can then be written like so,
using inline pragmas,
so that SVG can be used too:
`example-html.jsx`:
```js
/** @jsxImportSource hastscript */
console.log(
)
```
`example-svg.jsx`:
```js
/** @jsxImportSource hastscript/svg */
console.log(
SVG `<circle>` element
)
```
## 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,
`hastscript@9`,
compatible with Node.js 16.
## Security
Use of `hastscript` can open you up to a
[cross-site scripting (XSS)][wikipedia-xss]
when you pass user-provided input to it because values are injected into the
syntax tree.
The following example shows how an image is injected that fails loading and
therefore runs code in a browser.
```js
const tree = h()
// Somehow someone injected these properties instead of an expected `src` and
// `alt`:
const otherProps = {onError: 'alert(1)', src: 'x'}
tree.children.push(h('img', {src: 'default.png', ...otherProps}))
```
Yields:
```html
```
The following example shows how code can run in a browser because someone stored
an object in a database instead of the expected string.
```js
const tree = h()
// Somehow this isn’t the expected `'wooorm'`.
const username = {
type: 'element',
tagName: 'script',
children: [{type: 'text', value: 'alert(2)'}]
}
tree.children.push(h('span.handle', username))
```
Yields:
```html
alert(2)
```
Either do not use user-provided input in `hastscript` or use
[`hast-util-santize`][github-hast-util-sanitize].
## Related
* [`unist-builder`][github-unist-builder]
— create unist trees
* [`xastscript`][github-xastscript]
— create xast trees
* [`hast-to-hyperscript`](https://github.com/syntax-tree/hast-to-hyperscript)
— turn hast into React, Preact, Vue, etc
* [`hast-util-to-html`](https://github.com/syntax-tree/hast-util-to-html)
— turn hast into HTML
* [`hast-util-to-dom`](https://github.com/syntax-tree/hast-util-to-dom)
— turn hast into DOM trees
* [`estree-util-build-jsx`](https://github.com/syntax-tree/estree-util-build-jsx)
— compile JSX away
## Contribute
See
[`contributing.md`][health-contributing]
in
[`syntax-tree/.github`][health]
for ways to get started.
See [`support.md`][health-support] for ways to get help.
This project has a [code of conduct][health-coc].
By interacting with this repository,
organization,
or community you agree to abide by its terms.
## License
[MIT][file-license] © [Titus Wormer][wooorm]
[api-child]: #child
[api-h]: #hselector-properties-children
[api-properties]: #properties-1
[api-result]: #result
[api-s]: #sselector-properties-children
[badge-build-image]: https://github.com/syntax-tree/hastscript/workflows/main/badge.svg
[badge-build-url]: https://github.com/syntax-tree/hastscript/actions
[badge-coverage-image]: https://img.shields.io/codecov/c/github/syntax-tree/hastscript.svg
[badge-coverage-url]: https://codecov.io/github/syntax-tree/hastscript
[badge-downloads-image]: https://img.shields.io/npm/dm/hastscript.svg
[badge-downloads-url]: https://www.npmjs.com/package/hastscript
[badge-size-image]: https://img.shields.io/bundlejs/size/hastscript
[badge-size-url]: https://bundlejs.com/?q=hastscript
[esmsh]: https://esm.sh
[file-license]: license
[github-gist-esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
[github-hast]: https://github.com/syntax-tree/hast
[github-hast-element]: https://github.com/syntax-tree/hast#element
[github-hast-root]: https://github.com/syntax-tree/hast#root
[github-hast-text]: https://github.com/syntax-tree/hast#text
[github-hast-util-parse-selector]: https://github.com/syntax-tree/hast-util-parse-selector
[github-hast-util-sanitize]: https://github.com/syntax-tree/hast-util-sanitize
[github-unist-builder]: https://github.com/syntax-tree/unist-builder
[github-xastscript]: https://github.com/syntax-tree/xastscript
[health]: https://github.com/syntax-tree/.github
[health-coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md
[health-contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md
[health-support]: https://github.com/syntax-tree/.github/blob/main/support.md
[npmjs-install]: https://docs.npmjs.com/cli/install
[typescript]: https://www.typescriptlang.org
[wikipedia-xss]: https://en.wikipedia.org/wiki/Cross-site_scripting
[wooorm]: https://wooorm.com