Modification of structures stored in a localStorage in JavaScript

Let some array be saved in a local storage:

let arr = [1, 2, 3, 4, 5]; localStorage.setItem('data', JSON.stringify(arr));

Suppose now we need to somehow modify this array, for example, add one more element to the end of it or change an existing one.

To solve the problem, we retrieve a string with an array stored in the storage, convert this string into an array, perform the necessary manipulations with this array, convert this array back into a string and write it back to the storage:

let json = localStorage.getItem('data'); let data = JSON.parse(json); data.push(6); data[0] = '!'; localStorage.setItem('data', JSON.stringify(data));

Given the following array with users:

let users = [ { surn: 'surn1', name: 'name1', age: 31, }, { surn: 'surn2', name: 'name2', age: 32, }, { surn: 'surn', name: 'name3', age: 33, }, ];

Save it to a local storage. Then make 3 inputs and a button. Let the last name, first name and age be entered into the inputs. By clicking on the button, write the new user to the end of the array saved in the storage.