Package Exports

lit-element
lit-element/lit-element
lit-element/lit-element.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (lit-element) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

lit-element

Implements lit-html via a LitElement class. Made for custom Elements.

New in 0.4.0

We now allow you to switch out the standard lit-html render and html functions
You can now use lit-html-extended via lit-element-extended.js
Added notify option for properties, which will fire an event, if the value changes
A lot of bug fixes

New in 0.3.0

You can now set any property of your element to a promise and LitElement will set the property to the resolved value of the promise. (credit: depeele)
Attributes of properties with reflectToAttribute: true are now transformed to kebab-case. (credit: depeele)
Codebase moved to TypeScript.

Installation

You can get it through npm or yarn

npm install lit-element

yarn add lit-element

Default Usage

// import html from lit-html
import {html} from '../node-modules/lit-html/lit-html.js'

// import lit-element
import {LitElement} from '../node_modules/lit-element/lit-element.js'

// define Custom Element
class MyElement extends LitElement(HTMLElement) {

    // define properties similiar to Polymer 2/3
    static get properties() {
        return {
            title: String,
            body: {
                type: String,
                value: 'That is a cool LitElement',
                observer: '_bodyChanged',
                reflectToAttribute: true,
                notify: true
            }
        }
    }
    
    // define your template in render
    render() {
        this.title = 'This is lit';
        return html`
            <h1 id="title">${this.title}</h1>
            <p>${this.body}</h1>
        `;
    }

    // observer callback
    _bodyChanged(newValue) {
        console.log(`Body updated to ${newValue}`);
    }

    // If you want work done after the first render, like accessing elements with ids, do it here
    afterRender(isFirstRender) {
        if(isFirstRender) {
            // access the element with id 'title'
            this.$.title.classList.add('title--main');
            this.addEventListener('body-changed', e => {
                const body = e.detail;
                ...
            })
        }
    }
}

Notes

This Element does not use Polymer, just Polymer-like syntax for properties.
Currently only type, reflectToAttribute, observer, value and notify are supported for properties.