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pingjs

JavaScript ping API for use in a web browser context. Released under the BSD-3-Clause license, see LICENSE.

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greatest.deepsurf.us/scripts/370057/610490/pingjs.js 

// See LICENSE for usage information

// The following lines allow the ping function to be loaded via commonjs, AMD,
// and script tags, directly into window globals.
// Thanks to https://github.com/umdjs/umd/blob/master/templates/returnExports.js
(function (root, factory) { if (typeof define === 'function' && define.amd) { define([], factory); } else if (typeof module === 'object' && module.exports) { module.exports = factory(); } else { root.ping = factory(); }
}(this, function () {

    /**
     * Creates and loads an image element by url.
     * @param  {String} url
     * @return {Promise} promise that resolves to an image element or
     *                   fails to an Error.
     */
    function request_image(url) {
        return new Promise(function(resolve, reject) {
            var img = new Image();
            img.onload = function() { resolve(img); };
            img.onerror = function() { reject(url); };
            img.src = url + '?random-no-cache=' + Math.floor((1 + Math.random()) * 0x10000).toString(16);
        });
    }

    /**
     * Pings a url.
     * @param  {String} url
     * @param  {Number} multiplier - optional, factor to adjust the ping by.  0.3 works well for HTTP servers.
     * @return {Promise} promise that resolves to a ping (ms, float).
     */
    function ping(url, multiplier) {
        return new Promise(function(resolve, reject) {
            var start = (new Date()).getTime();
            var response = function() { 
                var delta = ((new Date()).getTime() - start);
                delta *= (multiplier || 1);
                resolve(delta); 
            };
            request_image(url).then(response).catch(response);
            
            // Set a timeout for max-pings, 5s.
            setTimeout(function() { reject(Error('Timeout')); }, 5000);
        });
    }
    
    return ping;
}));