将对象推入javascript深度或浅度拷贝的数组中吗？

Question

漂亮的自我明显的问题...当在javascript中对数组使用.push（）时，是将对象推入数组中的指针（浅）还是实际对象（深），而不管的类型。

Answer 1

这取决于你在推什么。对象和数组被作为指向原始对象的指针推送。像数字或布尔值这样的内置原始类型会作为副本推送。所以，由于对象没有以任何方式复制，因此它们没有深度或浅度的副本。

这里有一个工作片断显示它：

var array = []; 
 
var x = 4; 
 
var y = {name: "test", type: "data", data: "2-27-2009"}; 
 

 
// primitive value pushes a copy of the value 4 
 
array.push(x);    // push value of 4 
 
x = 5;      // change x to 5 
 
console.log(array[0]);  // array still contains 4 because it's a copy 
 

 
// object reference pushes a reference 
 
array.push(y);    // put object y reference into the array 
 
y.name = "foo";    // change y.name property 
 
console.log(array[1].name); // logs changed value "foo" because it's a reference

Answer 2

jfriend00是正确的标记在这里，但一个小的澄清：这并不意味着你不能改变你的变量指向。也就是说，y首先会引用一些变量，你放入数组，但你可以采取命名y变量，从现在的数组中的对象断开，并连接y（即使其参考）完全不同的东西而不更改现在仅由数组引用的对象。

http://jsfiddle.net/rufwork/5cNQr/6/

var array = []; 
var x = 4; 
var y = {name: "test", type: "data", data: "2-27-2009"}; 

// 1.) pushes a copy 
array.push(x); 
x = 5; 
document.write(array[0] + "<br>"); // alerts 4 because it's a copy 

// 2.) pushes a reference 
array.push(y); 
y.name = "foo"; 

// 3.) Disconnects y and points it at a new object 
y = {}; 
y.name = 'bar'; 
document.write(array[1].name + ' :: ' + y.name + "<br>"); 
// alerts "foo :: bar" because y was a reference, but then 
// the reference was moved to a new object while the 
// reference in the array stayed the same (referencing the 
// original object) 

// 4.) Uses y's original reference, stored in the array, 
// to access the old object. 
array[1].name = 'foobar'; 
document.write(array[1].name + "<br>"); 
// alerts "foobar" because you used the array to point to 
// the object that was initially in y.