Update specific value of object in localStorage

Question

I want to update the dataId field of an object in localStorage. Object:

let responseJson = {
                      id: user.id,
                      username: user.username,
                      firstName: user.firstName,
                      dataId: 1000
                   };

I am tring using following code:

let loggedInUser = localStorage.getItem('user_id');
JSON.parse(loggedInUser).userId = parseInt(2000);
localStorage.setItem('user_id', loggedInUser);

Updated:

let loggedInUser = localStorage.getItem('user_id');
loggedInUser.dataId = parseInt(2000);
console.log('loggedInUser', JSON.stringify(loggedInUser));
localStorage.setItem('user_id', JSON.stringify(loggedInUser));

You need to `JSON.stringify` `loggedInUser` object when saving to `localStorage` — Harun Yilmaz, Jan 29 '20 at 08:21
@HarunYilmaz Yeah I updated my code but still there is no value changed in localStorage — Varinder Sohal, Jan 29 '20 at 08:25
You're not modifying the `loggedInUser` value, you're modifying the parsed value, which is should be assigned to a variable, and then reencoded. — FMCorz, Jan 29 '20 at 08:27

Merci Dieu KIMPOLO · Accepted Answer · 2020-01-29T09:20:05.873

3

This can help:

let responseJson = {
                      id: user.id,
                      username: user.username,
                      firstName: user.firstName,
                      dataId: 1000
                   };

let loggedInUser = JSON.parse(localStorage.getItem('user_id'));
loggedInUser.dataId = parseInt(2000);
localStorage.setItem('user_id', JSON.stringify(loggedInUser));

edited Jan 29 '20 at 09:20

answered Jan 29 '20 at 08:24

Merci Dieu KIMPOLO

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its not working – Varinder Sohal Jan 29 '20 at 09:04
Hello @VarinderSohal, what are your getting an error? – Merci Dieu KIMPOLO Jan 29 '20 at 09:13
can't assign to property "dataId" on {} : not an object – Varinder Sohal Jan 29 '20 at 09:33
Can you update your code by sharing what you have currently? – Merci Dieu KIMPOLO Jan 29 '20 at 09:36
Code update has done you can see it – Varinder Sohal Jan 29 '20 at 09:42
Replace: let loggedInUser = localStorage.getItem('user_id'); By: let loggedInUser = JSON.parse(localStorage.getItem('user_id')); – Merci Dieu KIMPOLO Jan 29 '20 at 09:44
Thankyou it's working now – Varinder Sohal Jan 29 '20 at 09:53

score 1 · Answer 2 · answered Jan 29 '20 at 08:22

In localStorage, all values must be of type string. So, you have to stringify your object before storing it.

localStorage.setItem('user_id', JSON.stringify(loggedInUser))

BTW: You should check the user_id value before parsing it (or encapsulate in a try/catch).

Jai · Answer 3 · 2020-01-29T09:54:49.773

1

You can do something like this and you should stringify it before setting to localStorage:

let loggedInUser = JSON.parse(localStorage.getItem('user_id'));
let loggedInUserObj = {...loggedInUser, dataId : 2000}; // <---should be dataId
localStorage.setItem('user_id', JSON.stringify(loggedInUserObj));

Note:- You are not updating the dataId property but userId.

edited Jan 29 '20 at 09:54

answered Jan 29 '20 at 08:23

Jai

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Thankyou for your reply but your code just added new field not updated current available filed. – Varinder Sohal Jan 29 '20 at 08:55
@VarinderSohal oh yes. you should parse the string to object before and then destructure it to update. and one thing in your question you have posted to update the `userId` not `dataId`. – Jai Jan 29 '20 at 09:56

Update specific value of object in localStorage

3 Answers3