Update a specific data in LocalStorage.

Task 1.1: Store a user data

    let user = { id: 101, name:"Sachin", active:0 };
    localStorage.setItem("USER",JSON.stringify(user));

Task 1.2: Update the field from active=0 to active=1 and store it back in localStorage

    let selectedUser = JSON.parse(localStorage.getItem("USER"));
    console.log(selectedUser);
    //update the field - active from 0 to 1
    selectedUser["active"]=1;
    //write it back to localStorage
    localStorage.setItem("USER", JSON.stringify(user));

Task 2.1: Store multiple users data

    let user1 = { id: 101, name:"Sachin", active:0 };
    let user2 = { id: 102, name:"Dhoni", active:0 };
    let users = [user1, user2];
    localStorage.setItem("USERS",JSON.stringify(users));

Task 3.2: Update active field from 0 to 1 for user who has id=102

    let userId = 102; // For this user, we are going to update active from 0 to 1
    //Get users data from LocalStorage.
    let users = JSON.parse(localStorage.getItem("USERS")) || [];
    console.log(users);

    let index = users.findIndex(obj=>obj.id == userId ); //It will return index = 1
    let selectedUser = users[index]; // Get the user object 
    console.log(selectedUser);

    // update active from 0 to 1
    selectedUser["active"] = 1;
    users[index] = selectedUser; // Assign the updated user object back to array.

    //write the updated users array to localStorage
    localStorage.setItem("USERS", JSON.stringify(users));