javascript对象的深度克隆/复制

Deep cloning/copy for javascript objects

本文关键字：复制深度对象 javascript 更新时间：2023-09-26

在寻找深度复制包含嵌套和循环结构的对象的方法时，在循环引用和原型继承方面，这两种方法（1、2、3、4）都没有完美的解决方案。

我在这里编写了自己的实现。它能很好地完成任务还是算是一个更好的解决方案？

 /*
    a function for deep cloning objects that contains other nested objects and circular structures.
    objects are stored in a 3D array, according to their length (number of properties) and their depth in the original object.
                                    index (z)
                                         |
                                         |
                                         |
                                         |
                                         |
                                         |                      depth (x)
                                         |_ _ _ _ _ _ _ _ _ _ _ _
                                        /_/_/_/_/_/_/_/_/_/
                                       /_/_/_/_/_/_/_/_/_/
                                      /_/_/_/_/_/_/...../
                                     /................./
                                    /.....            /
                                   /                 /
                                  /------------------
            object length (y)    /
*/

function deepClone(obj) {
    var i = -1, //depth of the current object relative to the passed 'obj'
        j = 0;  //number of the object's properties
    var arr = new Array(); //3D array to store the references to objects
    return clone(obj, arr, i, j);
}
function clone(obj, arr, i ,j){
    if (typeof obj !== "object") {
        return obj;
    }
    var result = Object.create(Object.getPrototypeOf(obj)); //inherit the prototype of the original object
    if(result instanceof Array){
        result.length = Object.keys(obj).length;
    }
    i++; //depth is increased because we entered an object here
    j = Object.keys(obj).length; //native method to get the number of properties in 'obj'
    arr[i] = new Array(); //this is the x-axis, each index here is the depth
    arr[i][j] = new Array(); //this is the y-axis, each index is the length of the object (aka number of props)
    //start the depth at current and go down, cyclic structures won't form on depths more than the current one
    for(var depth = i; depth >= 0; depth--){
        //loop only if the array at this depth and length already have elements
        if(arr[depth][j]){
            for(var index = 0; index < arr[depth][j].length; index++){
                if(obj === arr[depth][j][index]){
                    return obj;
                }
            } 
        }
    }
    arr[i][j].push(obj); //store the object in the array at the current depth and length
    for (var prop in obj) {
        result[prop] = clone(obj[prop], arr, i, j);
    }
    return result;
}

你能试试下面的简单逻辑吗。将js对象转换为新的String，然后再次转换为对象。

例如：

var car = {type:"Fiat", model:"500", color:"white"};
var cloneStr = new String(JSON.stringify(car));
var carClone = JSON.parse(cloneStr);
carClone.type = "Maruthi";
alert(JSON.stringify(car)) ;
alert(JSON.stringify(carClone)) ;