等到所有的jQuery的Ajax请求都做了什么？ [英] Wait until all jQuery Ajax requests are done?

问题描述

我如何做一个函数等待，直到所有的jQuery的Ajax请求在另一个函数做了什么？

How do I make a function wait until all jQuery Ajax requests are done inside another function?

总之，我需要等待所有的Ajax请求完成之前，我执行下一步。但如何？

In short, I need to wait for all Ajax requests to be done before I execute the next. But how?

推荐答案

其实，现在jQuery的定义了一个何时功能，用于这一目的。

Actually, jQuery now defines a 'when' function for this purpose.

http://api.jquery.com/jQuery.when/

它接受任何数目的延迟对象作为参数，并执行在所有这些解决功能。

It accepts any number of Deferred objects as arguments, and executes a function when all of them resolve.

这意味着，如果你想要启动（例如）四Ajax请求，然后执行一个动作都完成时，他们，你可以做这样的事情：

That means, if you want to initiate (for example) four ajax requests, then perform an action when they are done, you could do something like this:

$.when(ajax1(), ajax2(), ajax3(), ajax4()).done(function(a1, a2, a3, a4){
    // the code here will be executed when all four ajax requests resolve.
    // a1, a2, a3 and a4 are lists of length 3 containing the response text,
    // status, and jqXHR object for each of the four ajax calls respectively.
});

function ajax1() {
    // NOTE:  This function must return the value 
    //        from calling the $.ajax() method.
    return $.ajax({
        url: "someUrl",
        dataType: "json",
        data:  yourJsonData,            
        ...
    });
}

在我看来，它使一个干净，清晰的语法，并避免涉及任何全局变量，如ajaxStart和ajaxStop，这可能会产生有害的副作用为你的网页的发展。

In my opinion, it makes for a clean and clear syntax, and avoids involving any global variables such as ajaxStart and ajaxStop, which could have unwanted side effects as your page develops.

如果你不事先知道你需要等待多少AJAX的参数（例如，你想使用可变数量的参数），它仍然可以做，但只是一点点麻烦。请参见通在Deferreds至$。当（）（也许<一个数组href="http://stackoverflow.com/questions/9865586/jquery-when-troubleshooting-with-variable-number-of-arguments">jQuery 。当故障排除与可变数量的参数）。

If you don't know in advance how many ajax arguments you need to wait for (i.e. you want to use a variable number of arguments), it can still be done but is just a little bit trickier. See Pass in an array of Deferreds to $.when() (and maybe jQuery .when troubleshooting with variable number of arguments).

如果您需要更深入的控制权的AJAX脚本等故障模式，您可以通过保存。当（）返回的对象 - 这是一个jQuery的无极对象包括所有原AJAX查询。你可以调用。那么（）或.fail（）就可以添加详细的成功/失败的处理程序。

If you need deeper control over the failure modes of the ajax scripts etc., you can save the object returned by .when() - it's a jQuery Promise object encompassing all of the original ajax queries. You can call .then() or .fail() on it to add detailed success/failure handlers.

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