lit-html

lit-html

Efficient, Expressive, Extensible HTML templates in JavaScript

Documentation

Full documentation is available at lit-html.polymer-project.org.

Docs source is in the docs folder. To build the site yourself, see the instructions in docs/README.md.

Overview

lit-html lets you write HTML templates in JavaScript with template literals.

lit-html templates are plain JavaScript and combine the familiarity of writing HTML with the power of JavaScript. lit-html takes care of efficiently rendering templates to DOM, including efficiently updating the DOM with new values.

import {html, render} from 'lit-html';

// This is a lit-html template function. It returns a lit-html template.
const helloTemplate = (name) => html`<div>Hello ${name}!</div>`;

// This renders <div>Hello Steve!</div> to the document body
render(helloTemplate('Steve'), document.body);

// This updates to <div>Hello Kevin!</div>, but only updates the ${name} part
render(helloTemplate('Kevin'), document.body);

lit-html provides two main exports:

• html: A JavaScript template tag used to produce a TemplateResult, which is a container for a template, and the values that should populate the template.
• render(): A function that renders a TemplateResult to a DOM container, such as an element or shadow root.

Installation

$ npm install lit-html

Forward compatibility with lit-html 2.0

lit-html 2.0 has a new directive authoring API that has been back-ported to lit-html 1.4 in order to ease upgrading.

The lit-html 2.0 directive API is available in new modules whose paths are the same in lit-html 1.4 and 2.0, allowing code to import and use the APIs against either version.

You can import the new APIs like so:

import {html} from 'lit-html';
import {directive, Directive, Part, PartInfo, PartType} from 'lit-html/directive.js';

Then implement a directive class and convert it to a directive function:

class MyDirective extends Directive {
  // ...
}
/** My directive docs **/
export const myDirective = directive(MyDirective);

Important note: The AsyncDirective base class is available, but lit-html 1.4 does not implement the disconnected and reconnected callbacks.

For more details on upgrading see the Update custom directive implementations guide.

Contributing

Please see CONTRIBUTING.md.