克隆对象数组的"sub-array"(其中对象深度嵌套)

Question

问题1。我想知道为什么

JSON.parse(JSON.stringify(obj.slice(1, 3))) and
obj.slice(1,3) 

给出相同的嵌套对象数组作为输出，因为obj.slice(1,3)不应该正确克隆嵌套对象?

问题2。JSON.parse(JSON.stringify(obj.slice(1, 3)))是深度克隆子阵列的正确方法吗?

obj details -

var obj= [{ name: "wfwfwfw.)csdfsd",
        tags: [ "dfbdf>>sfdfds", "fsdfsdf&fsfd" ],
        newer: { first: "this'one", second: ["that>.one", "another.'one"], third: {something: "some/>fded", newthing: "ddasd..>sqw"}     },
        final: [ {gh: "ty/fgfg", hj: "rt((ssds"}, {gh: "dqqq...g", hj: "gnm))s"} ]
},
{ name: "wfwfwwwwwwfw.)csdfsd",
        tags: [ "dfbdf>>sfdfds", "fsdfsdf&fsfd" ],
        newer: { first: "this'one", second: ["that>.one", "another.'one"], third: {something: "some/>fded", newthing: "ddasd..>sqw"} },
        final: [ {gh: "ty/fgfg", hj: "rt((ssds"}, {gh: "dqqq...g", hj: "gnm))s"}]
},
{ name: "aa.)csdfsd",
        tags: [ "dfbdf>>sfdfds", "fsdfsdf&fsfd" ],
        newer: { first: "this'one", second: ["that>.one", "another.'one"], third: {something: "some/>fded", newthing: "ddasd..>sqw"} },
        final: [ {gh: "ty/fgfg", hj: "rt((ssds"}, {gh: "dqqq...g", hj: "gnm))s"}]
},
{ name: "nn.)csdfsd",
        tags: [ "dfbdf>>sfdfds", "fsdfsdf&fsfd" ],
        newer: { first: "this'one", second: ["that>.one", "another.'one"], third: {something: "some/>fded", newthing: "ddasd..>sqw"} },
        final: [ {gh: "ty/fgfg", hj: "rt((ssds"}, {gh: "dqqq...g", hj: "gnm))s"}]
}]

Answer 1

如果JSON.parse(JSON.stringify())是obj.slice(1, 3)的结果，或者不是，为什么会有区别?这就是例1中发生的事情。

你得到obj.slice(1, 3)，你得到相同的值，通过stringify/parse传递。

功能上类似于:

var foo = 'bar';
console.log(foo);
console.log(JSON.parse(JSON.stringify(foo)));

关于问题2:

易普.

obj.slice不能单独用于克隆对象。它只是复制数组内容。在本例中，这些内容只是指向现有对象的指针:

var a = [{foo: 'bar'}, {x: 'y'}];
var b = a.slice(0,1) 
console.log('B:', b);
b[0].foo = 'test';
console.log('After modification:');
console.log('A:', a);
console.log('B:', b);

可以看到，在b上编辑foo也会在a上修改它，因为两个数组都包含指向相同对象的指针。

这就是为什么你需要JSON.parse(JSON.stringify())。

Answer 2

Array.slice()不做深度复制，因此不适合多维数组。

jQuery的extend方法在传递一个真值作为初始参数时执行深度复制。

// Deep copy
var newArray = jQuery.extend(true, [], oldArray);

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