JS對象復制(深拷貝和淺拷貝)

一、淺拷貝

1、Object.assign(target,source,source…)

a、可支持多個對象復制

b、如果source和target屬性相同 source會復制target的屬性

c、target隻能為Object對象

var obj = {a:1,b:2}
undefined
Object.assign({c:3},obj)
{c: 3, a: 1, b: 2}
obj
{a: 1, b: 2} 
兼容性寫法if(Object.assign){//兼容}else{//不兼容}

2、擴展運算符(spread)

支持將多個對象復制到一個對象上“

var obj1 = { foo: "foo" };
var obj2 = { bar: "bar" };
 
var copySpread = { ...obj1, ...obj2 }; // Object {foo: "foo", bar: "bar"}
copySpread 
{foo: "foo", bar: "bar"}
var obj = {a:1,b:2,c:3}
var objs = {...obj}
objs
{a: 1, b: 2, c: 3}
objs.a=10
10
objs
{a: 10, b: 2, c: 3}
obj
{a: 1, b: 2, c: 3}

二、深拷貝

1、使用對象序列化 JSON.stringify()和JSON.parse()

註意:此方法僅在原對象包含可序列化值類型且沒有任何循環引用時才有效。不可序列化值類型的一個例子是Date對象 -JSON.parse隻能將其解析為字符串而無法解析回其原始的Date對象 或者對象中屬性值為function

var obj = {a:1,b:[1,2,3],c:{e:3},bool:false}
undefined
var objs = JSON.parse(JSON.stringify(obj))
undefined
objs
{a: 1, b: Array(3), c: {…}, bool: false}
objs.bool = true
true
objs
{a: 1, b: Array(3), c: {…}, bool: true}
obj
{a: 1, b: Array(3), c: {…}, bool: false}

2、使用遞歸,對對象屬性進行判斷

function deepClone(obj) {
  var copy;
 
  // 如果 obj 是 null、undefined 或 不是對象,直接返回 obj
  // 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] = clone(obj[i]);
    }
    return copy;
  }
 
  // Handle Function
  if (obj instanceof Function) {
    copy = function() {
      return obj.apply(this, arguments);
    }
    return copy;
  }
 
  // Handle Object
  if (obj instanceof Object) {
      copy = {};
      for (var attr in obj) {
          if (obj.hasOwnProperty(attr)) copy[attr] = clone(obj[attr]);
      }
      return copy;
  }
 
  throw new Error("Unable to copy obj as type isn't supported " + obj.constructor.name);
}

以上就是JS對象復制(深拷貝和淺拷貝)的詳細內容,更多關於JS的資料請關註WalkonNet其它相關文章!