JAVASCRIPT

modify array elements javascript

Using a FOR loop, write a function addNumber which adds the argument n to each 
number in the array arr and returns the updated arr:
const addNumber=(arr, n)=>{  
  let arr1=[];
  for(let i=0;i<Math.max(arr.length);i++){
    arr1.push((arr[i]||0)+n)
  }
  return arr1;
} 
console.log(addNumber([4, 5, 6], 7)); // expected log [11, 12, 13]

change one element in array javascript

var users = [
{id: 1, firstname: 'John', lastname: 'Ken'},
{id: 2, firstname: 'Robin', lastname: 'Hood'},
{id: 3, firstname: 'William', lastname: 'Cook'}
];

var editedUser = {id: 2, firstname: 'Michael', lastname: 'Angelo'};

users = users.map(u => u.id !== editedUser.id ? u : editedUser);

console.log('users -> ', users);
 Run code snippet

JavaScript Change the Elements of an Array

let dailyActivities = [ 'eat', 'sleep'];

// this will add the new element 'exercise' at the 2 index
dailyActivities[2] = 'exercise';

console.log(dailyActivities); // ['eat', 'sleep', 'exercise']