Function.prototype.call.call的简写？ [英] A shorthand for Function.prototype.call.call?

问题描述

考虑这个简单的函数：

Consider this simple function:

function my(p) { console.log(p) }

我可以这样称呼它：

my("Hello");

同样如此：

And also like so:

my.call(this, "Hello");

此外，这是可能的：

Moreover, this is possible:

Function.prototype.call.call(my, this, "Hello");

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功能方式的简写

我对最后一个选项感兴趣 - 最实用的选项，但由于时间太长，我试图做一个简写：

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A shorthand for the functional way

I am interested in the last option - the most functional one, but since it's too long I tried to make a shorthand:

var call = Function.prototype.call.call;

为了像这样打电话给我：

in order to call my like this:

call(my, this, "Hello");

但是我得到这个TypeError：

But I get this TypeError:

TypeError: Function.prototype.call called on incompatible undefined

任何人知道，这里有什么问题？

Anybody knows, what's wrong here?

推荐答案

当您说

var call = Function.prototype.call.call;

上一次调用会丢失其实际上下文。你需要明确地说，调用属于 Function.prototype.call 。

the last call loses its actual context. You need to explicitly say that the call belongs to Function.prototype.call.

你可以通过创建一个新的函数来实现，像这样绑定它

You can do that, by creating a new function, which actually binds it like this

var call = Function.prototype.call.call.bind(Function.prototype.call);
call(my, this, "Hello");
// Hello

绑定函数返回一个新的函数，当被调用的时候，上下文（ this ）被设置为 Function.prototype.call 。

The bind function returns a new function, which when invoked will have the context (this) set as Function.prototype.call.

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