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Hyperscript Tagged Markup: JSX alternative using standard tagged templates, with compiler support.
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developit/htm
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htm isJSX-like syntax in plain JavaScript - no transpiler necessary.
Develop with React/Preact directly in the browser, then compilehtm away for production.
It uses standard JavaScriptTagged Templates and works inall modern browsers.
🐣< 600 bytes when used directly in the browser
⚛️< 500 bytes when used with Preact(thanks gzip 🌈)
🥚< 450 bytehtm/mini version
🏅0 bytes if compiled usingbabel-plugin-htm
The syntax you write when using HTM is as close as possible to JSX:
- Spread props:
<div ...${props}>instead of<div {...props}> - Self-closing tags:
<div /> - Components:
<${Foo}>instead of<Foo>(whereFoois a component reference) - Boolean attributes:
<div draggable />
htm actually takes the JSX-style syntax a couple steps further!
Here's some ergonomic features you get for free that aren't present in JSX:
- No transpiler necessary
- HTML's optional quotes:
<div class=foo> - Component end-tags:
<${Footer}>footer content<//> - Syntax highlighting and language support via thelit-html VSCode extension andvim-jsx-pretty plugin.
- Multiple root element (fragments):
<div /><div /> - Support for HTML-style comments:
<div><!-- comment --></div>
htm is published to npm, and accessible via the unpkg.com CDN:
via npm:
npmihtm
hotlinking from unpkg:(no build tool needed!)
importhtmfrom'https://unpkg.com/htm?module'consthtml=htm.bind(React.createElement);
// just want htm + preact in a single file? there's a highly-optimized version of that:import{html,render}from'https://unpkg.com/htm/preact/standalone.module.js'
If you're using Preact or React, we've included off-the-shelf bindings to make your life easier.They also have the added benefit of sharing a template cache across all modules.
import{render}from'preact';import{html}from'htm/preact';render(html`<ahref="/">Hello!</a>`,document.body);
Similarly, for React:
importReactDOMfrom'react-dom';import{html}from'htm/react';ReactDOM.render(html`<ahref="/">Hello!</a>`,document.body);
Sincehtm is a generic library, we need to tell it what to "compile" our templates to.You can bindhtm to any function of the formh(type, props, ...children)(hyperscript).This function can return anything -htm never looks at the return value.
Here's an exampleh() function that returns tree nodes:
functionh(type,props, ...children){return{ type, props, children};}
To use our customh() function, we need to create our ownhtml tag function by bindinghtm to ourh() function:
importhtmfrom'htm';consthtml=htm.bind(h);
Now we have anhtml() template tag that can be used to produce objects in the format we created above.
Here's the whole thing for clarity:
importhtmfrom'htm';functionh(type,props, ...children){return{ type, props, children};}consthtml=htm.bind(h);console.log(html`<h1id=hello>Hello world!</h1>`);// {// type: 'h1',// props: { id: 'hello' },// children: ['Hello world!']// }
If the template has multiple element at the root levelthe output is an array ofh results:
console.log(html`<h1id=hello>Hello</h1><divclass=world>World!</div>`);// [// {// type: 'h1',// props: { id: 'hello' },// children: ['Hello']// },// {// type: 'div',// props: { class: 'world' },// children: ['world!']// }// ]
The default build ofhtm caches template strings, which means that it can return the same Javascript object at multiple points in the tree. If you don't want this behaviour, you have three options:
- Change your
hfunction to copy nodes when needed. - Add the code
this[0] = 3;at the beginning of yourhfunction, which disables caching of created elements. - Use
htm/mini, which disables caching by default.
Curious to see what it all looks like? Here's a working app!
It's a single HTML file, and there's no build or tooling. You can edit it with nano.
<!DOCTYPE html><htmllang="en"><title>htm Demo</title><scripttype="module">import{html,Component,render}from'https://unpkg.com/htm/preact/standalone.module.js';classAppextendsComponent{addTodo(){const{ todos=[]}=this.state;this.setState({todos:todos.concat(`Item${todos.length}`)});}render({ page},{ todos=[]}){returnhtml`<divclass="app"><${Header}name="ToDo's (${page})"/><ul>${todos.map(todo=>html`<likey=${todo}>${todo}</li> `)}</ul><buttononClick=${()=>this.addTodo()}>Add Todo</button><${Footer}>footer content here<//></div> `;}}constHeader=({ name})=>html`<h1>${name} List</h1>`constFooter=props=>html`<footer...${props}/>`render(html`<${App}page="All"/>`,document.body);</script></html>
How nifty is that?
Notice there's only one import - here we're using the prebuilt Preact integration since it's easier to import and a bit smaller.
The same example works fine without the prebuilt version, just using two imports:
import{h,Component,render}from'preact';importhtmfrom'htm';consthtml=htm.bind(h);render(html`<${App}page="All"/>`,document.body);
Sincehtm is designed to meet the same need as JSX, you can use it anywhere you'd use JSX.
Generate HTML usingvhtml:
importhtmfrom'htm';importvhtmlfrom'vhtml';consthtml=htm.bind(vhtml);console.log(html`<h1id=hello>Hello world!</h1>`);// '<h1>Hello world!</h1>'
Webpack configuration viajsxobj: (details here)(never do this)
importhtmfrom'htm';importjsxobjfrom'jsxobj';consthtml=htm.bind(jsxobj);console.log(html`<webpackwatchmode=production><entrypath="src/index.js"/></webpack>`);// {// watch: true,// mode: 'production',// entry: {// path: 'src/index.js'// }// }
- Canadian Holidays: A full app using HTM and Server-Side Rendering
- HTM SSR Example: Shows how to do SSR with HTM
- HTM + Preact SSR Demo
- HTM + vhtml SSR Demo
The original goal forhtm was to create a wrapper around Preact that felt natural for use untranspiled in the browser. I wanted to use Virtual DOM, but I wanted to eschew build tooling and use ES Modules directly.
This meant giving up JSX, and the closest alternative wasTagged Templates. So, I wrote this library to patch up the differences between the two as much as possible. The technique turns out to be framework-agnostic, so it should work great with any library or renderer that works with JSX.
htm is stable, fast, well-tested and ready for production use.
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Hyperscript Tagged Markup: JSX alternative using standard tagged templates, with compiler support.