对象的Javascript变量赋值返回字符串 [英] Javascript variable assignment of object returns string

问题描述

我正在尝试运行以下代码：

I am trying to run the following code:

var status = null;
$.ajax({
    type: "GET",
    url: "/status",
    success: function(data, textStatus, jqXHR){
        status = data;
    },
    error: function(jqXHR, textStatus, errorThrown){
        console.error(textStatus + ": " + errorThrown);
    }
});

有趣的部分是以下行： status = data;

The interesting part is the following line: status = data;

在调试器中我可以看到 data 的值为 Object {7100665：0,8800798：0} 。 jQuery正确地将从服务器返回的JSON字符串解析为一个对象。

In the debugger I can see that data has the value Object {7100665: 0, 8800798: 0}. jQuery correctly parses the JSON-string returned from the server into an object.

然而，一行后面的全局变量 status 的值为[object Object]，其行为类似于字符串对象 - 字符串没有按预期分配给它的对象。

However, one line later the global variable status has the value "[object Object]" and behaves like a string object - string does not have the object assigned to it as expected.

在分配中看起来有一个隐含的 typeof 调用，这不可能，对吧？是否还有一些我不知道的事情？ ajax调用的 Content-Type 是 application / json 。

It looks like there was an implicite typeof call in the assignment going on, which cannot be, right? Is there some more going on that I am not aware of? The Content-Type of the ajax call is application/json.

我错过了什么/做错了什么？

What am I missing/doing wrong?

推荐答案

status 作为全局变量实际上是 窗口。 status ，这是一个（非标准）主机对象，可让您在实现它的浏览器中操作状态栏的文本。它的值被假定为一个字符串，因此你赋给它的任何值都将被静默强制转换成一个字符串。

status as a global variable is actually window.status, which is a (non-standard) host object that lets you manipulate the text of the status bar in browsers that implement it. Its value is assumed to be a string, so any value that you assign to it will be silently coerced into a string.

真正的问题是你污染了它带变量的全局范围。使用IIFE，这不是问题：

The real problem is that you're polluting the global scope with variables. Use an IIFE and this will not be an issue:

(function() {
    var status = null;
})();

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