Question

我一直在阅读克隆，每个人似乎都在使用一些复杂的代码。我想我可能做错了，但似乎工作正常，并且当改变＆＃34;克隆＆＃34;的价值时对象属性，我的主要对象不会改变。

var clonedObject ={};
//randomItem is main object, which I want to clone
for (var key in randomItem) {
    if (randomItem.hasOwnProperty(key)) {
        clonedObject[key] = {};
        clonedObject[key] = randomItem[key];
    }
};
return clonedObject;

它对我有用，请告诉我这是否有问题？我很困惑，因为与其他帖子所说的相比，这似乎太容易了（其中一些是7岁）。感谢

Answer 1

以下是一个快速示例，您可以看到代码与嵌套对象相比如何与真正的深度克隆相比：

var x = {a:{a:1}};

function update () {
  document.getElementById('x').textContent = JSON.stringify(x);
  document.getElementById('y').textContent = JSON.stringify(y);
  document.getElementById('z').textContent = JSON.stringify(z);
}

// This is your code
function yourClone (randomItem) {
  var clonedObject ={};
  for (var key in randomItem) {
    if (randomItem.hasOwnProperty(key)) {
      clonedObject[key] = {};
      clonedObject[key] = randomItem[key];
    }
  };
  return clonedObject;
}

// This is a real deep clone taken from http://stackoverflow.com/questions/728360/most-elegant-way-to-clone-a-javascript-object
function deepClone (obj) {
  var copy;

  // Handle the 3 simple types, and null or undefined
  if (null == obj || "object" != typeof obj) return obj;

  // Handle Date
  if (obj instanceof Date) {
    copy = new Date();
    copy.setTime(obj.getTime());
    return copy;
  }

  // Handle Array
  if (obj instanceof Array) {
    copy = [];
    for (var i = 0, len = obj.length; i < len; i++) {
      copy[i] = deepClone(obj[i]);
    }
    return copy;
  }

  // Handle Object
  if (obj instanceof Object) {
    copy = {};
    for (var attr in obj) {
      if (obj.hasOwnProperty(attr)) copy[attr] = deepClone(obj[attr]);
    }
    return copy;
  }

  throw new Error("Unable to copy obj! Its type isn't supported.");
}


function inc() {
  x.a.a++;
  update();
}

<body onload="y=yourClone(x);z=deepClone(x);update()">
  x: <span id="x"></span><br/>
  y: <span id="y"></span> &lt;- your clone from 'x'<br/>
  z: <span id="z"></span> &lt;- real deep clone from 'x'<br/><br/>
  <button id="inc" onclick="inc()">Increment nested element in x</button>
</body>

当您将某个变量的值复制到另一个变量时，根据数据类型，您将复制值本身（数字和文本）或仅复制数据（日期，数组和对象）。处理引用时，您需要递归进入下一级别并将所有值复制到新对象中以创建新实例。

Answer 2

// Shallow copy
var newObject = jQuery.extend({}, oldObject);

// Deep copy
var newObject = jQuery.extend(true, {}, oldObject);

What is the most efficient way to deep clone an object in JavaScript?

在nodeJS中使用下划线模块

让newObj = _.clone（oldObj）;

我正在克隆/复制javascript对象。我做得对吗？

2 个答案: