hast utility to create trees with ease.
- What is this?
- When should I use this?
- Install
- Use
- API
- Syntax tree
- JSX
- Compatibility
- Security
- Related
- Contribute
- License
This package is a hyperscript interface (like createElement from React and
h from Vue and such) to help with creating hast trees.
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
when creating any unist nodes and
xastscript when creating xast (XML) nodes.
This package is ESM only. In Node.js (version 16+), install with npm:
npm install hastscriptIn Deno with esm.sh:
import {h} from 'https://esm.sh/hastscript@9'In browsers with esm.sh:
<script type="module">
import {h} from 'https://esm.sh/hastscript@9?bundle'
</script>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 `<circle>` element'),
s('circle', {cx: 120, cy: 120, r: 100})
])
)Yields:
{
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 `<circle>` element'}]
},
{
type: 'element',
tagName: 'circle',
properties: {cx: 120, cy: 120, r: 100},
children: []
}
]
}This package exports the identifiers h and s.
There is no default export.
It exports the additional TypeScript types
Child,
Properties,
and
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.
Create virtual hast trees for HTML.
h(): rooth(null[, …children]): rooth(selector[, properties][, …children]): element
Simple CSS selector
(string, optional).
When string, builds an Element.
When nullish, builds a 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.
Properties of the element
(Properties, optional).
Children of the node (Child or Array<Child>, optional).
Created tree (Result).
Element when a selector is passed,
otherwise Root.
Create virtual 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.
(Lists of) children (TypeScript type).
When strings or numbers are encountered,
they are turned into Text
nodes.
Root nodes are treated as “fragments”,
meaning that their children are used instead.
type Child =
| Array<Node | number | string | null | undefined>
| Node
| number
| string
| null
| undefinedMap of properties (TypeScript type). Keys should match either the HTML attribute name or the DOM property name, but are case-insensitive.
type Properties = Record<
string,
| boolean
| number
| string
| null
| undefined
// For comma- and space-separated values such as `className`:
| Array<number | string>
// Accepts value for `style` prop as object.
| Record<string, number | string>
>Result from a h (or s) call (TypeScript type).
type Result = Element | RootThe syntax tree is hast.
This package can be used with JSX.
You should use the automatic JSX runtime set to hastscript or
hastscript/svg.
👉 Note while
hsupports dots (.) for classes or number signs (#) for IDs inselector, 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(ors) yourself and define it as the pragma (plus set the fragment tonull).
The Use example above can then be written like so, using inline pragmas, so that SVG can be used too:
example-html.jsx:
/** @jsxImportSource hastscript */
console.log(
<div class="foo" id="some-id">
<span>some text</span>
<input type="text" value="foo" />
<a class="alpha bravo charlie" download>
deltaecho
</a>
</div>
)example-svg.jsx:
/** @jsxImportSource hastscript/svg */
console.log(
<svg xmlns="http://www.w3.org/2000/svg" viewbox="0 0 500 500">
<title>SVG `<circle>` element</title>
<circle cx={120} cy={120} r={100} />
</svg>
)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.
Use of hastscript can open you up to a
cross-site scripting (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.
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:
<img onerror="alert(1)" src="x">The following example shows how code can run in a browser because someone stored an object in a database instead of the expected string.
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:
<span class="handle"><script>alert(2)</script></span>Either do not use user-provided input in hastscript or use
hast-util-santize.
unist-builder— create unist treesxastscript— create xast treeshast-to-hyperscript— turn hast into React, Preact, Vue, etchast-util-to-html— turn hast into HTMLhast-util-to-dom— turn hast into DOM treesestree-util-build-jsx— compile JSX away
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.
