我只是在阅读this question并想尝试使用别名方法而不是函数包装方法，但我似乎无法让它在 Firefox 3 或 3.5beta4 或 Google Chrome 中工作，无论是在调试窗口还是在测试网页中。

Firebug :

>>> window.myAlias = document.getElementById
function()
>>> myAlias('item1')
>>> window.myAlias('item1')
>>> document.getElementById('item1')
<div id="item1">

uncaught exception: [Exception... "Illegal operation on WrappedNative prototype object" nsresult: "0x8057000c (NS_ERROR_XPC_BAD_OP_ON_WN_PROTO)" location: "JS frame :: file:///[...snip...]/test.html :: <TOP_LEVEL> :: line 7" data: no]

>>> window.myAlias = document.getElementById
function getElementById() { [native code] }
>>> window.myAlias('item1')
TypeError: Illegal invocation
>>> document.getElementById('item1')
<div id=?"item1">?

最佳答案

我深入研究以了解这种特殊行为，并且我认为我找到了一个很好的解释。

在我解释为什么你不能使用别名 document.getElementById 之前，我将尝试解释 JavaScript 函数/对象是如何工作的。

每当您调用 JavaScript 函数时，JavaScript 解释器都会确定一个范围并将其传递给该函数。

考虑以下功能:

function sum(a, b)
{
    return a + b;
}

sum(10, 20); // returns 30;

function Person(birthDate)
{
    this.birthDate = birthDate;    
    this.getAge = function() { return new Date().getFullYear() - this.birthDate.getFullYear(); };
}

var dave = new Person(new Date(1909, 1, 1)); 
dave.getAge(); //returns 100.

var dave = new Person(new Date(1909, 1, 1)); //Age 100 in 2009
var bob = new Person(new Date(1809, 1, 1)); //Age 200 in 2009

dave.getAge.apply(bob); //returns 200.

var dave = new Person(new Date(1909, 1, 1));
var bob = new Person(new Date(1809, 1, 1));

bob.getAge = function() { return -1; };

bob.getAge(); //returns -1
dave.getAge(); //returns 100

var dave = new Person(new Date(1909, 1, 1));
var ageMethod = dave.getAge;

dave.getAge(); //returns 100;
ageMethod(); //returns ?????

ageMethod.apply(dave); //returns 100.

var $ = document.getElementById;

$('someElement'); 

$.apply(document, ['someElement']);

function Person(birthDate)
{
    var self = this;

    this.birthDate = birthDate;

    this.getAge = function()
    {
        //Let's make sure that getAge method was invoked 
        //with an object which was constructed from our Person function.
        if(this.constructor == Person)
            return new Date().getFullYear() - this.birthDate.getFullYear();
        else
            return -1;
    };

    //Smarter version of getAge function, it will always refer to the object
    //it was created with.
    this.getAgeSmarter = function()
    {
        return self.getAge();
    };

    //Smartest version of getAge function.
    //It will try to use the most appropriate scope.
    this.getAgeSmartest = function()
    {
        var scope = this.constructor == Person ? this : self;
        return scope.getAge();
    };

}

var yogi = new Person(new Date(1909, 1,1)); //Age is 100
var anotherYogi = new Person(new Date(1809, 1, 1)); //Age is 200

console.log(yogi.getAge()); //Output: 100.

var ageAlias = yogi.getAge;
console.log(ageAlias()); //Output: -1

console.log(ageAlias.apply(yogi)); //Output: 100

console.log(ageAlias.apply(anotherYogi)); //Output: 200

var ageSmarterAlias = yogi.getAgeSmarter;    
console.log(ageSmarterAlias()); //Output: 100

console.log(ageSmarterAlias.apply(anotherYogi)); //Output: 100 !!!

var ageSmartestAlias = yogi.getAgeSmartest;
console.log(ageSmartestAlias()); //Output: 100
console.log(ageSmartestAlias.apply(document)); //Output: 100

console.log(ageSmartestAlias.apply(anotherYogi)); //Output: 200

关于JavaScript 函数别名似乎不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/1007340/