Three implementations of JS deep copy-1024programmer

Three implementations of JS deep copy

1. Convert the object into a JSON string, and then convert it into a native JS object;

//_tmp and result are independent of each other, have no connection, and have their own storage space.
 let deepClOne = function (obj) {
     let _tmp = JSON.stringify(obj);//Convert the object to json string form
     let result = JSON.parse(_tmp);//Convert the converted string to a native js object
     return result;
 };

 let obj1 = {
     weiqiujaun: {
         age: 20,
         class: 1502
     },
     liuxiaotian: {
         age: 21,
         class: 1501
     }
 };

 let test = deepClone(obj1);
 console.log(test);

2. Use the for loop in JS to traverse and copy;

function deepClone(obj)  {
     let result = typeof obj. splice === "function" ? [] : {};
     if (obj && typeof obj === 'object') {
         for (let key in obj) {
             if (obj[key] && typeof obj[key] === 'object') {
                 result[key] = deepClone(obj[key]);//If the attribute value of the object is object, call deepClone recursively, that is, copy a value object to the corresponding value of the new object.
             } else {
                 result[key] = obj[key];//If the attribute value of the object is not object, directly copy each key value of the parameter object to the key-value pair corresponding to the new object.
             }

         }
         return result;
     }
     return obj;
 }

 let testArray = ["a", "b", "c", "d"];
 let testRes = deepClone(testArray);
 console.log(testRes);
 console.log(typeof testRes[1]);

 let testObj = {
     name: "weiqiujuan",
     sex: "girl",
     age: 22,
     favorite: "play",
     family: {brother: "son", mother: "haha", father: "heihei"}
 };
 let testRes2 = deepClone(testObj);
 testRes2.family.brother = "weibo";
 console.log(testRes2);

3. Use the “Array.prototype.forEach” method of the array to copy to realize deep copy.

let deepClOne= function (obj) {
     let copy = Object.create(Object.getPrototypeOf(obj));
     let propNames = Object. getOwnPropertyNames(obj);
     propNames. forEach(function (items) {
         let item = Object. getOwnPropertyDescriptor(obj, items);
         Object.defineProperty(copy, items, item);

     });
     return copy;
 };

 let testObj = {
     name: "weiqiujuan",
     sex: "girl",
     age: 22,
     favorite: "play",
     family: {brother: "wei", mother: "haha", father: "heihei"}
 }
 let testRes2 = deepClone(testObj);
 console.log(testRes2);