克隆Javascript/Typescript中的数组 [英] Cloning an array in Javascript/Typescript

问题描述

我有两个对象组成的数组:

I have array of two objects:

genericItems: Item[] = [];
backupData: Item[] = [];

我正在用genericItems数据填充HTML表.该表是可修改的.有一个重置按钮可以撤消使用backUpData完成的所有更改.此数组由服务填充:

I am populating my HTML table with genericItemsdata. The table is modifiable. There is a reset button to undo all changes done with backUpData. This array is populated by a service:

getGenericItems(selected: Item) {
this.itemService.getGenericItems(selected).subscribe(
  result => {
     this.genericItems = result;
  });
     this.backupData = this.genericItems.slice();
  }

我的想法是，用户更改将反映在第一个阵列中，而第二个阵列可以用作重置操作的备份.我在这里面临的问题是用户修改表时(genericItems[])第二个数组backupData也被修改了.

My idea was that, the user changes will get reflected in first array and second array can be used as backup for reset operation. The issue I am facing here is when the user modifies the table (genericItems[]) the second array backupData also gets modified.

这是怎么回事，如何预防呢?

How is this happening and how to prevent this?

推荐答案

尝试一下:

克隆对象:

const myClonedObject = Object.assign({}, myObject);

克隆数组:

选项1-如果您具有原始类型的数组:

Option 1 - if you have an array of primitive types:

const myClonedArray  = Object.assign([], myArray);

选项2-如果您有对象数组:(感谢@mumblesNZ)

Option 2 - if you have an array of objects: (thanks @mumblesNZ)

const myArray= [{ a: 'a', b: 'b' }, { a: 'c', b: 'd' }]; 
const myClonedArray = []; 
myArray.forEach(val => myClonedArray.push(Object.assign({}, val)));

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