…每个对象在同一个数组中也有对其他对象的引用?

当我第一次想到这个问题的时候,我就想到了

var clonedNodesArray = nodesArray.clone()

并搜索如何在JavaScript中克隆对象的信息。我确实在Stack Overflow上找到了一个问题(同样由@JohnResig回答),他指出用jQuery你可以做到

var clonedNodesArray = jQuery.extend({}, nodesArray);

克隆对象。虽然我尝试了这个,但这只复制了数组中对象的引用。如果我

nodesArray[0].value = "red"
clonedNodesArray[0].value = "green"

nodesArray[0]和clonedNodesArray[0]的值将显示为“绿色”。然后我尝试了

var clonedNodesArray = jQuery.extend(true, {}, nodesArray);

它深度复制了一个对象,但我分别从Firebug和Opera Dragonfly得到了“太多递归”和“控制堆栈溢出”的消息。

你会怎么做?这是不应该做的事情吗?在JavaScript中是否有可重用的方法来做到这一点?


当前回答

var game_popularity = [
     { game: "fruit ninja", popularity: 78 },
     { game: "road runner", popularity: 20 },
     { game: "maze runner", popularity: 40 },
     { game: "ludo", popularity: 75 },
     { game: "temple runner", popularity: 86 }
];
console.log("sorted original array before clonning");
game_popularity.sort((a, b) => a.popularity < b.popularity);
console.log(game_popularity);


console.log("clone using object assign");
const cl2 = game_popularity.map(a => Object.assign({}, a));
cl2[1].game = "clash of titan";
cl2.push({ game: "logan", popularity: 57 });
console.log(cl2);


// Adding new array element doesnt reflect in original array
console.log("clone using concat");
var ph = []
var cl = ph.concat(game_popularity);

// Copied by reference ?
cl[0].game = "rise of civilization";

game_popularity[0].game = 'ping me';
cl.push({ game: "angry bird", popularity: 67 });
console.log(cl);

console.log("clone using ellipses");
var cl3 = [...game_popularity];
cl3.push({ game: "blue whale", popularity: 67 });
cl3[2].game = "harry potter";
console.log(cl3);

console.log("clone using json.parse");
var cl4 = JSON.parse(JSON.stringify(game_popularity));
cl4.push({ game: "home alone", popularity: 87 });
cl4[3].game ="lockhead martin";
console.log(cl4);

console.log("clone using Object.create");
var cl5 = Array.from(Object.create(game_popularity));
cl5.push({ game: "fish ville", popularity: 87 });
cl5[3].game ="veto power";
console.log(cl5);


// Array function
console.log("sorted original array after clonning");
game_popularity.sort((a, b) => a.popularity < b.popularity);
console.log(game_popularity);


console.log("Object.assign deep clone object array");
console.log("json.parse deep clone object array");
console.log("concat does not deep clone object array");
console.log("ellipses does not deep clone object array");
console.log("Object.create does not deep clone object array");

输出

sorted original array before clonning
[ { game: 'temple runner', popularity: 86 },
{ game: 'fruit ninja', popularity: 78 },
{ game: 'ludo', popularity: 75 },
{ game: 'maze runner', popularity: 40 },
{ game: 'road runner', popularity: 20 } ]
clone using object assign
[ { game: 'temple runner', popularity: 86 },
{ game: 'clash of titan', popularity: 78 },
{ game: 'ludo', popularity: 75 },
{ game: 'maze runner', popularity: 40 },
{ game: 'road runner', popularity: 20 },
{ game: 'logan', popularity: 57 } ]
clone using concat
[ { game: 'ping me', popularity: 86 },
{ game: 'fruit ninja', popularity: 78 },
{ game: 'ludo', popularity: 75 },
{ game: 'maze runner', popularity: 40 },
{ game: 'road runner', popularity: 20 },
{ game: 'angry bird', popularity: 67 } ]
clone using ellipses
[ { game: 'ping me', popularity: 86 },
{ game: 'fruit ninja', popularity: 78 },
{ game: 'harry potter', popularity: 75 },
{ game: 'maze runner', popularity: 40 },
{ game: 'road runner', popularity: 20 },
{ game: 'blue whale', popularity: 67 } ]
clone using json.parse
[ { game: 'ping me', popularity: 86 },
{ game: 'fruit ninja', popularity: 78 },
{ game: 'harry potter', popularity: 75 },
{ game: 'lockhead martin', popularity: 40 },
{ game: 'road runner', popularity: 20 },
{ game: 'home alone', popularity: 87 } ]
clone using Object.create
[ { game: 'ping me', popularity: 86 },
{ game: 'fruit ninja', popularity: 78 },
{ game: 'harry potter', popularity: 75 },
{ game: 'veto power', popularity: 40 },
{ game: 'road runner', popularity: 20 },
{ game: 'fish ville', popularity: 87 } ]
sorted original array after clonning
[ { game: 'ping me', popularity: 86 },
{ game: 'fruit ninja', popularity: 78 },
{ game: 'harry potter', popularity: 75 },
{ game: 'veto power', popularity: 40 },
{ game: 'road runner', popularity: 20 } ]

Object.assign deep clone object array
json.parse deep clone object array
concat does not deep clone object array
ellipses does not deep clone object array
Object.create does not deep clone object array

其他回答

我可能有一种简单的方法来做到这一点,而不需要做痛苦的递归,也不知道有关对象的所有细节。使用jQuery,只需使用jQuery $. tojson (myObjectArray)将对象转换为JSON,然后将JSON字符串计算回对象。砰!搞定了,搞定了!问题解决了。:)

var oldObjArray = [{ Something: 'blah', Cool: true }];
var newObjArray = eval($.toJSON(oldObjArray));

在我的例子中,我有一个包含许多嵌套对象的数组,所以其他答案不适用于我的用例。

我现在使用的是npm包deep-copy-all:

npm i deep-copy-all
const deepCopy = require("deep-copy-all")

const copy = deepCopy(original)
copy[0].users[0].payments[0].product.price = 10

console.log(copy[0].users[0].payments[0].product.price) // 10
console.log(original[0].users[0].payments[0].product.price) // 5

我的方法:

var temp = { arr : originalArray };
var obj = $.extend(true, {}, temp);
return obj.arr;

给我一个漂亮的,干净的,深克隆的原始数组-没有对象引用回原始:-)

对于克隆对象,我只是建议ECMAScript 6 reduce():

const newArray = myArray.reduce((array, element) => array.push(Object.assign({}, element)), []);

但坦白说,我更喜欢恐龙的答案。我只是把这个版本放在这里作为另一个选择,但就我个人而言,我将使用map(),因为恐龙建议。

如果你只需要一个浅克隆,最好的方法如下:

使用…ES6扩展运算符。

这里有一个最简单的例子:

var clonedObjArray = [...oldObjArray];

通过这种方式,我们将数组扩展为单独的值,并使用[]操作符将其放入一个新数组中。

下面是一个更长的例子,展示了它的不同工作方式:

let objArray = [ {a:1} , {b:2} ]; let refArray = objArray; // this will just point to the objArray let clonedArray = [...objArray]; // will clone the array console.log( "before:" ); console.log( "obj array" , objArray ); console.log( "ref array" , refArray ); console.log( "cloned array" , clonedArray ); objArray[0] = {c:3}; console.log( "after:" ); console.log( "obj array" , objArray ); // [ {c:3} , {b:2} ] console.log( "ref array" , refArray ); // [ {c:3} , {b:2} ] console.log( "cloned array" , clonedArray ); // [ {a:1} , {b:2} ]