Detailed explanation of clone object/function code in javascript-JS Tutorial-php.cn

Detailed explanation of clone object/function code in javascript

伊谢尔伦

Release： 2017-07-27 17:11:15

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In JavaScript, the simple method is to use the JSON function to stringify the object into a string, and then parse it into a new object. Or just search for code from the Internet. There are still a lot of clone codes in the open source community.

Although the code can be found, things will always belong to others, and learning to code by hand will always be a constant theme.

Wrote two cloning functions:

cloneOwn: Clone the own properties of a custom object, excluding inherited properties. Properties can be basic data types and arrays, custom objects , you can formulate a list of attribute names to be cloned.

cloneArray: Clone an array. The elements in the array can be objects or basic types.

//第一个参数是被克隆的对象，第二个参数是需要克隆的属性列表
function cloneOwn() {
  var obj = arguments[0];
  if (typeof obj === &#39;undefined&#39; || obj === null)
      return {};
  if (typeof obj !== &#39;object&#39;)
      return obj;
  //第二个参数是属性名称列表，就采用该列表进行刷选
  //否则就克隆所有属性
  var attrs = arguments[1];
  var enable_spec_attr = true;
  if (!(attrs instanceof Array)) {
      //console.log(attrs);
      attrs = obj;
      enable_spec_attr = false;
  }
  var result = {};
  var i;
  for (i in attrs) {
      attr = enable_spec_attr? attrs[i]: i;
      //console.log(attr);
      if (obj.hasOwnProperty(attr)) {
          if (obj[attr] instanceof Array) {
              result[attr] = cloneArray(obj[attr]);
          }
          else if (typeof obj[attr] === &#39;object&#39;) {
              result[attr] = cloneOwn(obj[attr]);
          } else {
              result[attr] = obj[attr];
          }
      }
  }
  return result;
}

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//克隆数组
function cloneArray(array) {
  if (typeof array === &#39;undefined&#39; || array === null)
    return [];
  if (!(array instanceof Array))
    return [];
  result = [];
  var i;
  for(i in array) {
    if (typeof array[i] !== &#39;object&#39;) {
      result[i] = array[i];
      continue;
    }
    //clone object
    result[i] = cloneOwn(array[i]);
  }
  return result;
}

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Call

1. Regular clone custom object:

var a = {
    name:&#39;frank&#39;,
    age:20
};
var b= cloneOwn(a);

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2. Specify the attributes of the clone

var a = {
    name:&#39;frank&#39;,
    age:20,
    address:&#39;any where&#39;
};
var b = cloneOwne(a, [&#39;name&#39;, &#39;age&#39;]);

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3. Clone contains array attributes Custom object

var a = {
    name: &#39;kxh&#39;,
    age: 20,
    books: [&#39;hai&#39;,&#39;ho&#39;,&#39;ali&#39;],
    likes: [
        {wname: &#39;kaili&#39;, wage: 81, fav: "aaaaa"},
        {wname: &#39;seli&#39;, wage: 82, fav: "bbb"},
        {wname: &#39;ailun&#39;, wage: 83, fav: "ccc"},]
};
var b = cloneOwne(a);

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4. Clone array containing custom object

var a = [
   {
      name:&#39;frank&#39;,
      age:20
    },
    {
       name:&#39;leon&#39;,
       age:30
     }
];
var b = cloneArray(a);

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