Rewriting array elements in JavaScript

You can also read the current value of an element, perform some operation on it, and write the changed value back to that element:

let arr = ['a', 'b', 'c']; arr[0] = arr[0] + '!'; arr[1] = arr[1] + '!'; arr[2] = arr[2] + '!'; console.log(arr); // shows ['a!', 'b!', 'c!']

The previous code can be rewritten using the operator +=:

let arr = ['a', 'b', 'c']; arr[0] += '!'; arr[1] += '!'; arr[2] += '!'; console.log(arr); // shows ['a!', 'b!', 'c!']

Create an array with numbers. Add the number 3 to each element of the array. Display the modified array on the screen.