A decorator class to make listening to changes easy

Usage no npm install needed!

<script type="module">
  import litNotify from '';


Lit Notify

Lit Notify is a simple class extension for Lit Element that hooks in to the updated method and notifies callback methods (if defined) for changes to properties. Using Lit-Notify makes it eassier to listen to change. To illustrate how it works, have a look at the example.

Lit Notify is really lightweight and zero dependencies.


import { LitElement, html } from 'lit-element';
import { Notify } from 'lit-notify';

class AppComponents extends Notify(LitElement) {
    static get properties() {
        return {
            timestamp: {
                type: Number,
                changeCallback: 'timestampChanged'
            reset: {
            difference: Number
    connectedCallback() {
        this.interval = setInterval(() => {
            this.timestamp =;
        }, 6000 );
    updated(changedProperties) {
        if (changedPropeties.has('timestamp')) {
            console.log('timestamp has changed');
    timestampChanged(next, prev, key) {
        this.difference = prev ? next-prev : 0;
    __timestampChanged(next, prev, key) {
        // If you do not specify a callback in the properties
        // this will be the default method name that is being used.
        // If the method is not defined, it will not be called.
    render() {
        return html`<p>Timestamp difference: ${this.difference}</p>`;

In the exmple above you see that in the properties you can specify a callback method for when the property timestamp has changed. If you do not specify it a default name for a callback method will be used like __<propertyName>Changed, in our example its __timestampChanged

If you want to implement the updated method in your component class, you can still do so. Lit-Notify is only extending behaviour, not overriding your implementation.


Version Change description
1.0.0 Initial verison
1.0.1 Added repository details
1.1.0 Improved performance and added key as last param for debugging purposes