JavaScript ping API for use in a web browser context. Released under the BSD-3-Clause license, see LICENSE.
Tento skript by neměl být instalován přímo. Jedná se o knihovnu, kterou by měly jiné skripty využívat pomocí meta příkazu // @require https://update.greasyfork.org/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;
}));