@wordpress/dom-ready/src/index.js

Execute callback after the DOM is loaded.

/**
 * @typedef {() => void} Callback
 *
 * TODO: Remove this typedef and inline `() => void` type.
 *
 * This typedef is used so that a descriptive type is provided in our
 * automatically generated documentation.
 *
 * An in-line type `() => void` would be preferable, but the generated
 * documentation is `null` in that case.
 *
 * @see https://github.com/WordPress/gutenberg/issues/18045
 */

/**
 * Specify a function to execute when the DOM is fully loaded.
 *
 * @param {Callback} callback A function to execute after the DOM is ready.
 *
 * @example
 * ```js
 * import domReady from '@wordpress/dom-ready';
 *
 * domReady( function() {
 * 	//do something after DOM loads.
 * } );
 * ```
 *
 * @return {void}
 */
export default function domReady( callback ) {
	if ( typeof document === 'undefined' ) {
		return;
	}

	if (
		document.readyState === 'complete' || // DOMContentLoaded + Images/Styles/etc loaded, so we call directly.
		document.readyState === 'interactive' // DOMContentLoaded fires at this point, so we call directly.
	) {
		return void callback();
	}

	// DOMContentLoaded has not fired yet, delay callback until then.
	document.addEventListener( 'DOMContentLoaded', callback );
}