我有一个对象x。我想将其复制为对象y,这样对y的更改不会修改x。我意识到复制从内置JavaScript对象派生的对象会导致额外的、不需要的财产。这不是问题,因为我正在复制我自己的一个文字构造对象。
如何正确克隆JavaScript对象?
我有一个对象x。我想将其复制为对象y,这样对y的更改不会修改x。我意识到复制从内置JavaScript对象派生的对象会导致额外的、不需要的财产。这不是问题,因为我正在复制我自己的一个文字构造对象。
如何正确克隆JavaScript对象?
当前回答
不同的
仅复制顶层:{…object}和object.assign({},object)
让objA={a: “键a”,b:{c: “键c”,}}let objB=Object.assign({},objA);//或{…objB}//更改对象BobjB.a=“更改objA.a(顶部)”console.log(“objA.a(top)无更改:\n”+JSON.stringify(objA,false,2));objB.b.c=“更改应仅适用于objB.b.c,但在objA.b.c中”console.log(“objA.a.c第二级已更改:\n”+JSON.stringify(objA,false,2));
对于深度复制,请使用旧浏览器的structuredClone()2022或JSON.parse(JSON.stringify(object)),无需黑客即可轻松完成。
让objA={a: “键a”,b:{c: “键c”,}}让objB=typeof structuredClone==“函数”?structuredClone(objA):JSON.parse(JSON.stringify(objB));//更改对象BobjB.a=“更改objA.a(顶部)”objB.b.c=“更改应该只针对objB.c,但它在objA.c中”console.log(“objA没有更改:\n”+JSON.stringify(objA,false,2));
其他回答
我找到了一种用函数克隆对象的方法(打断多行以便于理解):
const clone = Object.assign(
Object.create(
Object.getPrototypeOf(originalObject)
),
dataObject
);
根据Airbnb JavaScript风格指南,有404位贡献者:
首选对象排列运算符而不是对象。指定为浅层复制物体。使用object rest操作符获取具有特定省略了财产。
// very bad
const original = { a: 1, b: 2 };
const copy = Object.assign(original, { c: 3 }); // this mutates `original` ಠ_ಠ
delete copy.a; // so does this
// bad
const original = { a: 1, b: 2 };
const copy = Object.assign({}, original, { c: 3 }); // copy => { a: 1, b: 2, c: 3 }
// good
const original = { a: 1, b: 2 };
const copy = { ...original, c: 3 }; // copy => { a: 1, b: 2, c: 3 }
const { a, ...noA } = copy; // noA => { b: 2, c: 3 }
此外,我想提醒您,尽管Airbnb几乎不建议使用对象扩散运算符方法。请记住,Microsoft Edge仍然不支持此2018功能。
ES2016+公司表>>
克隆对象的简单递归方法。也可以使用lodash.clone。
让克隆=(obj)=>{let obj2=Array.isArray(obj)?[] : {};for(设k为obj){obj2[k]=(obj[k]===“对象”的类型)?克隆(obj[k]):obj[k];}返回obj2;}让w={name:“Apple”,类型:[“Fuji”,“Gala”]};设x=克隆(w);w.name=“橙色”;w.types=[“Navel”];console.log(x);console.log(w);
我已经编写了自己的实现。不确定它是否算作更好的解决方案:
/*
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) /
*/
实施情况如下:
function deepClone(obj) {
var depth = -1;
var arr = [];
return clone(obj, arr, depth);
}
/**
*
* @param obj source object
* @param arr 3D array to store the references to objects
* @param depth depth of the current object relative to the passed 'obj'
* @returns {*}
*/
function clone(obj, arr, depth){
if (typeof obj !== "object") {
return obj;
}
var length = Object.keys(obj).length; // native method to get the number of properties in 'obj'
var result = Object.create(Object.getPrototypeOf(obj)); // inherit the prototype of the original object
if(result instanceof Array){
result.length = length;
}
depth++; // depth is increased because we entered an object here
arr[depth] = []; // this is the x-axis, each index here is the depth
arr[depth][length] = []; // 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 x = depth; x >= 0; x--){
// loop only if the array at this depth and length already have elements
if(arr[x][length]){
for(var index = 0; index < arr[x][length].length; index++){
if(obj === arr[x][length][index]){
return obj;
}
}
}
}
arr[depth][length].push(obj); // store the object in the array at the current depth and length
for (var prop in obj) {
if (obj.hasOwnProperty(prop)) result[prop] = clone(obj[prop], arr, depth);
}
return result;
}
根据Apple JavaScript编码指南:
// Create an inner object with a variable x whose default
// value is 3.
function innerObj()
{
this.x = 3;
}
innerObj.prototype.clone = function() {
var temp = new innerObj();
for (myvar in this) {
// this object does not contain any objects, so
// use the lightweight copy code.
temp[myvar] = this[myvar];
}
return temp;
}
// Create an outer object with a variable y whose default
// value is 77.
function outerObj()
{
// The outer object contains an inner object. Allocate it here.
this.inner = new innerObj();
this.y = 77;
}
outerObj.prototype.clone = function() {
var temp = new outerObj();
for (myvar in this) {
if (this[myvar].clone) {
// This variable contains an object with a
// clone operator. Call it to create a copy.
temp[myvar] = this[myvar].clone();
} else {
// This variable contains a scalar value,
// a string value, or an object with no
// clone function. Assign it directly.
temp[myvar] = this[myvar];
}
}
return temp;
}
// Allocate an outer object and assign non-default values to variables in
// both the outer and inner objects.
outer = new outerObj;
outer.inner.x = 4;
outer.y = 16;
// Clone the outer object (which, in turn, clones the inner object).
newouter = outer.clone();
// Verify that both values were copied.
alert('inner x is '+newouter.inner.x); // prints 4
alert('y is '+newouter.y); // prints 16
史蒂夫