无法访问变量 [英] Unable to access variable

问题描述

我有两个外部Javascript文件。我在一个文件中声明了一个变量，我试图从其他变量中访问变量。当我尝试访问它时，它返回 undefined 。

I have two external Javascript files. I declared a variable in one file and I am trying to access the variable from other. When I try to access it, it returns undefined.

<script src="script1.js"></script>
<script src="script2.js"></script>

script1 ：

script1:

$(function(){

    var myvar=35;
});

script2 ：

script2:

$(function(){

    alert(myvar); //this line causing error undefined.

});

推荐答案

您的变量不是全局的。你已经在一个函数内部声明了它，所以它是该函数的本地对象。您需要将 var 语句移到文档就绪函数之外

Your variable isn't global. You've declared it inside a function so it is local to that function. You need to move the var statement outside your document ready function:

var myvar=35;

$(function(){
    // other document ready stuff here, including
    // using or assigning a value to myvar if needed
});

然后它将被全局作用域并且可以从其他脚本文件访问（只要它们是包括在声明的那个之后）。

Then it will be globally scoped and can be accessed from other script files (as long as they're included after the one where it's declared).

如果在文档准备好之前您不知道要分配的值，请执行以下操作：

If you don't know the value to assign until the document ready then do this:

var myvar;       // declare variable

$(function(){
    myvar = 35;  // assign value
});

由于您不尝试使用该值，直到其他脚本的文档就绪处理程序运行，很好。

Since you don't try to use the value until the other script's document ready handler runs this would be fine.

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