Guides: Attributes

In custom elements, attributes must be pre-defined. To define what attributes your component supports, set the observedAttributes property on the function you defined. Note that attributes use kebab case in templates and are converted into camel case for use in your component's code.

import { component } from 'haunted';
function App({ firstName }) {
  return `Hello ${firstName}!`;
}

App.observedAttributes = ['first-name'];

customElements.define('my-app', component(App));

Alternatively, you can pass observedAttributes as an option to component():

import { component } from 'haunted';
function App({ firstName }) {
  return `Hello ${firstName}!`;
}

customElements.define('my-alt', component(App, { observedAttributes: ['first-name'] }));

Once your custom element is defined you can then pass in attributes as you would with any other HTML element. Just like any other HTML attribute only strings are accepted, anything else will be converted into a string.

<my-app first-name="World"></my-app>