梵蒂冈之花
根据Yair Leviel给出的答案，这个答案已经过时了。使用promise库，如jQuery.when（）或Q.js.我创建了一个通用解决方案作为jQuery扩展。可以使用一些微调使其更通用，但它符合我的需要。截至撰写本文时，此技术优于其他技术的优势在于可以使用任何类型的带回调的异步处理。注意：我会使用JavaScript的Rx扩展而不是这个，如果我认为我的客户端可以依赖于另一个第三方库:)// jQuery extension for running multiple async methods in parallel// and getting a callback with all results when all of them have completed.//// Each worker is a function that takes a callback as its only argument, and// fires up an async process that calls this callback with its result.//// Example:// $.parallel(// function (callback) { $.get("form.htm", {}, callback, "html"); },// function (callback) { $.post("data.aspx", {}, callback, "json"); },// function (formHtml, dataJson) { // // Handle success; each argument to this function is // // the result of correlating ajax call above.// }// );(function ($) {
$.parallel = function (anyNumberOfWorkers, allDoneCallback) {
var workers = [];
var workersCompleteCallback = null;
// To support any number of workers, use "arguments" variable to
// access function arguments rather than the names above.
var lastArgIndex = arguments.length - 1;
$.each(arguments, function (index) {
if (index == lastArgIndex) {
workersCompleteCallback = this;
} else {
workers.push({ fn: this, done: false, result: null });
}
});
// Short circuit this edge case
if (workers.length == 0) {
workersCompleteCallback();
return;
}
// Fire off each worker process, asking it to report back to onWorkerDone.
$.each(workers, function (workerIndex) {
var worker = this;
var callback = function () { onWorkerDone(worker, arguments); };
worker.fn(callback);
});
// Store results and update status as each item completes.
// The [0] on workerResultS below assumes the client only needs the first parameter
// passed into the return callback. This simplifies the handling in allDoneCallback,
// but may need to be removed if you need access to all parameters of the result.
// For example, $.post calls back with success(data, textStatus, XMLHttpRequest). If
// you need textStatus or XMLHttpRequest then pull off the [0] below.
function onWorkerDone(worker, workerResult) {
worker.done = true;
worker.result = workerResult[0]; // this is the [0] ref'd above.
var allResults = [];
for (var i = 0; i < workers.length; i++) {
if (!workers[i].done) return;
else allResults.push(workers[i].result);
}
workersCompleteCallback.apply(this, allResults);
}};})(jQuery);