AJAX-响应数据不会保存到全球范围有多大？ [英] AJAX- response data not saved to global scope?

问题描述

我有我的如下行不存储变量到全球范围问题：

I am having the issue of my below shown lines not storing the variable into the global scope:

var somedata;

$.ajax({
    cache: false,
    url: verification_url,
    success: function(data){
        somedata = data;
    }
});

alert(somedata); // Undefined

我是什么做错了吗？我是否需要包装成一个单独的函数或者是什么呢？

What am I doing wrong? Do I need to wrap this into a separate function or what?

推荐答案

在警报（） code从 $响应之前运行阿贾克斯被接收。

The alert() code runs before the response from $.ajax is received.

这就是为什么它是未定义。

var somedata;

$.ajax({
    cache: false,
    url: verification_url,
    success: function(data){
        somedata = data;

        alert( somedata );   // 2. this will occur after the response is received
    }
});

alert(somedata); // 1. this will occur first

在这里你可以看到，警报发生乱序。默认情况下AJAX请求不运行并不prevent随后code。

Here you can see that the alerts happen out of order. By default an AJAX request does not prevent subsequent code from running.

这是有一个的回调的方法的全部目的。它是不是依靠同步执行一个被调用在适当的时间的方法，

That's the entire purpose of having a callback method. It is a method that gets called at the appropriate time, instead of relying on synchronous execution.

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