使用JSON进行JavaScript深度复制 [英] javascript deep copy using JSON

问题描述

我对javascript对象(数组)深层复制有问题.我阅读了许多处理它的好方法.而且我也知道jQuery具有$ .extend API来解决此问题.但是我的问题是:我可以仅使用JSON stringify和parse方法来解决此问题吗?

I have problem with javascript object(array) deep copy. I read many good way to deal with it. And I also know that jQuery has $.extend API to this problem. But my question is: Can I just using JSON stringify and parse method to solve this problem?

这是我的代码:

function deepCopy(oldValue) { 
  var newValue
  strValue = JSON.stringify(oldValue)
  return newValue = JSON.parse(strValue)
}

var a = {
  b: 'b',
  c: [1,2,4],
  d: null
}

copy = deepCopy(a)

console.log(a === copy) // false
console.log(a.c === copy.c) // false

PS:我知道，如果没有所有对象都可以序列化，但是我所知道的唯一情况是，当对象包含一个函数属性时.还有其他情况吗?

PS: I've known that if no all objects are serializable, but the only situation I know is that when the object contains a property which is function. Any other situation?

推荐答案

如果您的对象很小"并且仅包含可序列化的属性，那么使用JSON序列化的简单deepCopy hack应该可以.但是，如果您的对象很大，则可能会遇到问题.如果它包含不可序列化的属性，则这些属性将丢失:

If your object is "small" and contains exclusively serializable properties, a simple deepCopy hack using JSON serialization should be OK. But, if your object is large, you could run into problems. And if it contains unserializable properties, those'll go missing:

var o = {
 a: 1,
 b: 2,
 sum: function() { return a + b; }
};

var o2 = JSON.parse(JSON.stringify(o));
console.log(o2);

收益:

Object {a: 1, b: 2}

^{足够有趣的是，C#中的大量深层复制解决方案都是类似的序列化/反序列化技巧.}

附录:不确定在复制后比较对象方面的期望.但是，对于复杂的对象，通常需要编写自己的Compare()和/或Equals()方法以进行准确的比较.

Addendum: Not sure what you're hoping for in terms of comparing the objects after the copy. But, for complex objects, you generally need to write your own Compare() and/or Equals() method for an accurate comparison.

同样值得注意的是，这种副本不会保留类型信息.

Also notable, this sort of copy doesn't preserve type information.

JSON.parse(JSON.stringify(new A())) instanceof A === false

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