javascript - 具有相同内容的变量不相等......为什么？

Question

这个问题已经有答案了:

Why isn't [1,2,3] equal to itself in Javascript? [duplicate] (6 个回答)

已关闭 9 年前。

如果两个变量内容相同，为什么我会收到 false？

function A() { return {k:'k'}; }
function B() { return {k:'k'}; }

var a = new A;
var b = new B;

 var s='';

for (prop in a) {
   if (typeof a[prop] != "function") {
       s += "a[" + prop + "] = " + a[prop] + "; ";
   }
}
alert(s);


for (prop in b) {
   if (typeof b[prop] != "function") {
       s += "b[" + prop + "] = " + b[prop] + "; ";
   }
}
alert(s);


alert( a == b ); // false?

http://jsfiddle.net/wZjPg/

即使我为 a 和 b 分配相同的函数，也会发生同样的情况

var obj = {};

function A() { return {k:'k'}; }

var a = new A;
var b = new A;

alert( a == b ); // false?

http://jsfiddle.net/3rzrR/

这里也一样

k={zor:1};
b={zor:1};

alert(k==b); //false

http://jsfiddle.net/5v8BJ/

Answer 1

这是因为对象是通过引用进行比较的。

[] === []; // false

根据https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Comparison_Operators ,

If both operands are objects, then JavaScript compares internal references which are equal when operands refer to the same object in memory.