@gravityforms/utils/src/dom/is-external-link.js

JavaScript utilities for Gravity Forms development.

/**
 * @module isExternalLink
 * @description Tests if an url is pointing to the same domain as the client or not.
 *
 * @since 1.0.0
 *
 * @param {string} url The url to test.
 *
 * @return {boolean} Whether the passed string is an external url or not.
 *
 * @example
 * import { isExternalLink } from "@gravityforms/utils";
 *
 * function Example() {
 *   const url = 'https://some-url.com';
 *   if ( isExternalLink( url ) ) {
 *       // do something
 *   }
 * }
 *
 */
export default function isExternalLink( url = '' ) {
	const match = url.match(
		/^([^:/?#]+:)?(?:\/\/([^/?#]*))?([^?#]+)?(\?[^#]*)?(#.*)?/
	);
	if (
		typeof match[ 1 ] === 'string' &&
		match[ 1 ].length > 0 &&
		match[ 1 ].toLowerCase() !== window.location.protocol
	) {
		return true;
	}

	return typeof match[ 2 ] === 'string' &&
		match[ 2 ].length > 0 &&
		match[ 2 ].replace(
			new RegExp(
				`:(${
					{
						'http:': 80,
						'https:': 443,
					}[ window.location.protocol ]
				})?$`
			),
			''
		) !== window.location.host;
}