处理来自多个AJAX JQuery的查询独立的数据 [英] Handling independant data from multiple AJAX JQuery queries

问题描述

我有一个数字，是从发送循环AJAX请求，并希望一些数据发送到回调函数取决于循环中的位置。

I have a number of AJAX requests that are sent from a for loop, and want to send some data to the call back functions depending on the position in the loop.

当我尝试将功能附加到每个请求，他们似乎都在最后一次通话中获取数据，例如，

When I try to attach a function to each request, they all seem to get the data from the last call, for instance,

for(var i=0; i < 4; i++){
    data = ... //some unique data
    req = $.post('/update/add', data, function(r_data, textStatus, jqxhr){
        console.log(data);
    }, "json")
}

将从I = 3项，而不是4个不同的项目给我的数据。我如何可以将这些数据传递给回调函数？

Would give me the data from the i = 3 entry instead of 4 different entries. How can I pass those data to the callback functions?

感谢你们......

Thank you guys...

推荐答案

现在的问题是，当一个闭包在我变量，创建，它引用相同的变量，而不是创建一个新的我变量。为了避免这种不良影响，你可以做到以下几点。

The problem is that when a closure is created over the i variable, it references the same variable instead of creating a new i variable. To avoid this undesirable effect, you can do the following.

for(var i=0; i < 4; i++){
    data = ... //some unique data
    req = $.post('/update/add', data, (function (i) {
        //return a new callback function
        return function (r_data, textStatus, jqxhr) { 
            //callback logic
            //i will be the right index now
        };
    })(i), "json");
}

在上面的例子中，我们包装在被传递回路的我值自动执行功能的回调函数。因为我变量是在自动执行功能的范围定义，我们现在可以安全地返回一个新的回调函数，将创建一个封闭在我的自动执行功能，而不是在循环使用的I 变量。

In the example above, we are wrapping our callback function in a self-executing function that is being passed the loop's i value. Since the i variable is defined in the scope of the self-executing function, we can now safely return a new callback function that will create a closure over the i variable of the self-executing function instead of the i variable used in the loop.

注：为了优化您的code，你能避免创建一个新的自动执行功能，每次

NOTE: To optimize your code, you could avoid creating a new self-executing function each time.

function createCallback(i) {
     return function (r_data, textStatus, jqxhr) {
         console.log(i);
     };
}

/*
    loop
        post(..., createCallback(i));
 */

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