@salesforce/design-system-react/utilities/warning/url-exists.js

Salesforce Lightning Design System for React

/* Copyright (c) 2015-present, salesforce.com, inc. All rights reserved */
/* Licensed under BSD 3-Clause - see LICENSE.txt or git.io/sfdc-license */

/* eslint-disable import/no-mutable-exports */
/* global XMLHttpRequest, window */

// This function does an "AJAX" request to warn users on how to setup their icon path.
import warning from 'warning';

let urlExists = function () {};

if (process.env.NODE_ENV !== 'production') {
	const hasWarned = {};
	let hasExecuted;

	// Using XMLHttpRequest can cause problems in non-browser environments. This should be completely removed in production environment and should not execute in a testing environment.
	urlExists = function (control, url, comment) {
		if (
			!hasExecuted &&
			!hasWarned[`${control}-path`] &&
			typeof window !== 'undefined' &&
			XMLHttpRequest &&
			process.env.NODE_ENV !== 'test'
		) {
			const http = new XMLHttpRequest();
			http.open('HEAD', url, false);
			http.send();
			hasExecuted = true;

			if (http.status === 404) {
				const additionalComment = comment ? ` ${comment}` : '';
				/* eslint-disable max-len */
				warning(
					!url,
					`The icon asset was not found at ${url}. Make sure the path to the icon asset is correct. You can set the icon path by importing the IconSettings component, \`<IconSettings iconPath=[/assets/icons]>\` from \`components/iconSettings\`, and wrap that component around your entire app or around individual components using icons. If you are using the \`<Icon>\` component, you can also pass the url to \`this.props.path\`.${additionalComment}`
				);
				/* eslint-enable max-len */
				hasWarned[`${control}-path`] = !!url;
			}
		}
	};
}

export default urlExists;