Provides a behavior for an element that validates user input

Usage no npm install needed!

<script type="module">
  import polymerIronValidatableBehavior from 'https://cdn.skypack.dev/@polymer/iron-validatable-behavior';


Published on NPM Build status Published on webcomponents.org


Use IronValidatableBehavior to implement an element that validates user input. By using this behaviour, your custom element will get a public validate() method, which will return the validity of the element, and a corresponding invalid attribute, which can be used for styling. Can be used alongside an element implementing the IronValidatableBehavior behaviour.

See: Documentation, Demo.



npm install --save @polymer/iron-validatable-behavior

In a Polymer 3 element

import {PolymerElement, html} from '@polymer/polymer';
import {mixinBehaviors} from '@polymer/polymer/lib/legacy/class.js';
import {IronValidatableBehavior} from '@polymer/iron-validatable-behavior/iron-validatable-behavior.js';

class SampleElement extends mixinBehaviors([IronValidatableBehavior], PolymerElement) {
  static get template() {
    return html`
        :host {
          border: 1px solid green;
          color: green;
        :host([invalid]) {
          border: 1px solid red;
          color: red;
      <input id="input">

    // Override this method if you want to implement custom validity
    // for your element. This element is only valid if the value in the
    // input is "cat".
    function _getValidity() {
      return this.$.input.value === 'cat';
customElements.define('sample-element', SampleElement);

In an html file using the element

    <script type="module" src="./sample-element.js"></script>
    <sample-element id="el"></sample-element>
    <button onclick="el.validate()">Validate!</button>


If you want to send a PR to this element, here are the instructions for running the tests and demo locally:


git clone https://github.com/PolymerElements/iron-validatable-behavior
cd iron-validatable-behavior
npm install
npm install -g polymer-cli

Running the demo locally

polymer serve --npm

Running the tests

polymer test --npm