Javascript array deep copy not working as expected

Asked Sep 17 '19 at 10:14

Active Sep 17 '19 at 10:51

Viewed 45 times

I have two javascript arrays. I need to copy the array values from one another. I have used code like below.

javascript

let firstArr = [{name: "one"},{name: "two"}];
let secondArr = [...firstArr];
secondArr[0].name = "three";
console.log(firstArr)
console.log(secondArr)

I have changed only "secondArr" values. But first array values are also changed. I have used the spread operator, so it will create a new memory then why the first array values are also changed?

Could you please anyone explain this. Thanks in advance.

edited Sep 17 '19 at 10:51

Alwaysblue

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asked Sep 17 '19 at 10:14

az rnd

2

`[...` only creates a shallow copy – CertainPerformance Sep 17 '19 at 10:15
If you look at MDN, you'll see this: *Note: Spread syntax effectively goes one level deep while copying an array. Therefore, it may be unsuitable for copying multidimensional arrays.* – Gerardo Furtado Sep 17 '19 at 10:27
use - `lodash.js` var firstArr = [{name: "one"},{name: "two"}]; var secondArr = _.cloneDeep([...firstArr]); secondArr[0].name = "three"; console.log(firstArr) console.log(secondArr) – Pritam Jana Sep 17 '19 at 10:28
Use `array.map()` method. – Daniyal Lukmanov Sep 17 '19 at 10:29

Javascript array deep copy not working as expected

0 Answers0