每个JavaScript对象都是一个函数吗？ [英] Is every JavaScript Object a function?
问题描述
是否有JavaScript对象不是函数？
javascript：x = y = z = Object; alert（[window.navigator.userAgent，x，y，z] .join（\\\
\\\
））
（有评论那 y ， z case Object 函数Object（）{...} 的引用，因为对象的值被分配给 x ，它们是相同的，作为证明
javascript：x = Object; xp = 43; alert（[x == Object，x === Object，xp，Object.p]）
显示
true ，true，43,43
给定函数Thing（）{} code>确实 x = new Thing（） make x 对象或对象的引用？ new Thing（）和 Thing ？或者 y in y = x = new Thing（）或 y = x = Thing ？如果 >事情=函数（）{} ？这个区别是没有意义的。 一切（或是否？）是通过引用来调用的，但是可以通过评估字符串来强制调用名称。所以...）
javascript：
void function（x，y，z）{
alert （[window.navigator.userAgent，x，y，z] .join（\\\
\\\
））
（Object，Object，Object）
或
javascript：
void function（x）{（function（y）{（function（z）{
alert（[window.navigator.userAgent，x，y，z] .join（\\\
\\\
））
$ b $（很好） moot - 必须使用（...）或来强制函数的值。（...）的细微差别很微妙： javascript：/ * 43.p给出了一个运行时错误，但不是...... * /
alert（[（43）.p = 34，43 [q] = 17，（x = 43）.z =hmmm]）;
alert（[43 [p]，（43）.z，xp，x [z]，x]）;
显示 34,17，hmmm 和 ,,,, 43
）
甚至是一个ar物体对象
javascript：alert（[window.navigator.userAgent，Object，Object，Object] .join（\ n $ \\ n））
给出：
Mozilla / 5.0（X11; U; Linux i686; EN-US; rv：1.9.2.3）Gecko / 20100423 Ubuntu / 10.04（lucid）Firefox / 3.6.3
function Object（）{
[native code]}
function Object（）{
[native code]}
function Object（）{
有许多对象不是Object。
正如在答案，对象可能不是自身如果它被修改。
危险！危险！ Will Robinson！
x = y = z = Object = null;警报（[window.navigator.userAgent，对象，X，Y，Z]。加入（ \\\
\\\
））;
引用
解决方案您没有创建对象，您创建了对对象的引用功能。如果你想让这些东西成为对象，你可以这样做：
x = y = z = {}
code>
然后 alert（x）将返回对象（希望）包含注释 - 默认情况下为 Object 。
是构造对象的函数。如果你重新命名Object（Firefox至少似乎允许我，并没有测试过所有的浏览器），那么 Object 将不再是一个Function，它会是你分配给它。那么，答案是否，Object不是始终是Function，而是应该是，除非它已被明确地重新声明。根据Firebug的说法：
>>> Object
Object（）
>>> Object = {}
Object {}
>>> Object
Object {}
看起来它可以被重新分配。如果有的话，我不能保证会有什么样的影响。
Is there a JavaScript Object that is not a function?
javascript: x=y=z=Object; alert([window.navigator.userAgent,x,y,z].join("\n\n"))
(There was a comment that x,y,z are merely references in which case Object is also merely a reference to function Object(){ ... } because Object's value is assigned to x and they are the "same". As "proof"
javascript:x=Object;x.p=43;alert([x==Object,x===Object,x.p,Object.p])
displays
true,true,43,43
Given function Thing(){} does x=new Thing() make x an object or a reference to one? What about new Thing() and Thing? Or y in y=x=new Thing() or y=x=Thing? What if Thing=function(){}? The distinction is moot. "Everything" (or is it?) is called-by-reference but call-by-name can be coerced by evaluating strings. So ...)
javascript:
void function(x,y,z){
alert( [window.navigator.userAgent,x,y,z].join("\n\n") )
}(Object,Object,Object)
or
javascript:
void function(x){ (function (y){ (function (z){
alert( [window.navigator.userAgent,x,y,z].join("\n\n") )
})(y) })(x) }(Object)
(well not quite moot - the function's values must be coerced using (...) or void. The nuances of (...) are subtle:
javascript: /* 43.p gives a runtime error but not ... */
alert([ (43).p=34, 43["q"]=17, (x=43).z="hmmm" ]);
alert([ 43["p"], (43).z, x.p, x["z"], x]);
displays 34,17,hmmm and ,,,,43
)
or even an array of Objects
javascript:alert([window.navigator.userAgent,Object,Object,Object].join("\n\n"))
gives:
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.3) Gecko/20100423 Ubuntu/10.04 (lucid) Firefox/3.6.3
function Object() {
[native code] }
function Object() {
[native code] }
function Object() {
[native code] }
There are many objects that are not Object.
As pointed out in one of the answers, Object may not be itself IF it is modified.
Danger! Danger! Will Robinson!
x=y=z=Object=null; alert([window.navigator.userAgent,Object,x,y,z].join("\n\n"));
references
- Object and Function are quite confusing
- Difference between a constructor and an Object
- Is Function really an Object
- Is JavaScript function a "function" or an "object" or both?
- Every Object is a function and every function is Object - Which is Correct?
- Why in JavaScript is a function considered both a constructor and an object?
解决方案 You didn't create objects, you created references to the Object function. If you wanted those to be objects you could do this:
x = y = z = {}
Then alert(x) will return object [Object].
To (hopefully) encompass the comments - by default Object is a Function which constructs Objects. If you reassign the name Object (Firefox at least seems to allow me to, haven't tested all browsers) then Object will no longer be a Function, it will be whatever you assigned to it. So then, the answer is "no", Object is not always a Function, but should be unless it has been explicitly re-declared. According to Firebug:
>>> Object
Object()
>>> Object = {}
Object {}
>>> Object
Object {}
Seemingly it can be reassigned. I cannot vouch for what kind of impacts that would have, if any.
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