JavaScript - 检查是否在全局上下文中
16lz
2021-01-22
When a function is attached to an object and called:
将函数附加到对象并调用时:
function f() { return this.x; }
var o = {x: 20};
o.func = f;
o.func(); //evaluates to 20
this refers to the object that the function was called as a method of. It's equivalent to doing f.call(o).
这指的是函数被称为方法的对象。这相当于做f.call(o)。
When the function is called not as part of an object, this refers to the global object. How do I check if a function is being called from a non-object context? Is there any standard keyword to access the global object? Is the only way to do it something like this?
当函数不是作为对象的一部分调用时,它指的是全局对象。如何检查是否从非对象上下文调用函数?是否有任何标准关键字可以访问全局对象?是这样做的唯一方法吗?
globalobj = this;
function f() { if (this == globalobj) doSomething(); }
Note: I have no particular use case in mind here - I actually am asking about this exact mechanism.
注意:我在这里没有特别的用例 - 我实际上是在询问这个确切的机制。
3 个解决方案
#1
The global object is actually the window so you can do
全局对象实际上是窗口,因此您可以这样做
if (this === window)
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