util.js

/**
 * The Util service is for thin, globally reusable, utility functions
 */

import {
    isFunction,
    noop,
} from 'lodash';

/**
 * Return a callback or noop function
 *
 * @param  {Function|*} cb - a 'potential' function
 * @return {Function}
 */
export function safeCb(cb) {
    return isFunction(cb) ? cb : noop;
}

/**
 * Parse a given url with the use of an anchor element
 *
 * @param  {String} url - the url to parse
 * @return {Object}     - the parsed url, anchor element
 */
export function urlParse(url) {
    var a = document.createElement('a');
    a.href = url;

    // Special treatment for IE, see http://stackoverflow.com/a/13405933 for details
    if (a.host === '') {
        // eslint-disable-next-line no-self-assign
        a.href = a.href;
    }

    return a;
}

/**
 * Test whether or not a given url is same origin
 *
 * @param  {String}           url       - url to test
 * @param  {String|String[]}  [origins] - additional origins to test against
 * @return {Boolean}                    - true if url is same origin
 */
export function isSameOrigin(url, origins) {
    url = urlParse(url);
    origins = (origins && [].concat(origins)) || [];
    origins = origins.map(urlParse);
    origins.push(window.location);
    origins = origins.filter(function(o) {
        let hostnameCheck = url.hostname === o.hostname;
        let protocolCheck = url.protocol === o.protocol;
        // 2nd part of the special treatment for IE fix (see above):
        // This part is when using well-known ports 80 or 443 with IE,
        // when window.location.port==='' instead of the real port number.
        // Probably the same cause as this IE bug: https://goo.gl/J9hRta
        let portCheck = url.port === o.port || (o.port === '' && (url.port === '80' || url.port === '443'));
        return hostnameCheck && protocolCheck && portCheck;
    });
    return origins.length >= 1;
}