Javascript - Replace multiple elements in an array using index

Question

Consider following array in Javascript:

var array1 = ['S', 'T', 'A', 'C', 'K', 'O', 'V', 'E', 'R', 'F', 'L', 'O', 'W'];

Now I want to replace all the elements at once from index 3 to 9 in following way:

array1 = ['S', 'T', 'A', 'X', 'X', 'X', 'X', 'X', 'X', 'X', 'L', 'O', 'W'];

Is it possible to achieve in javascript ?

Note: I want to perform following operation using array only

Answer 1

Use Array.fill()

var array1 = ['S', 'T', 'A', 'C', 'K', 'O', 'V', 'E', 'R', 'F', 'L', 'O', 'W'];

array1.fill('X', 3, 10)

console.log(array1)

Answer 2

Use array splice() method

var array1= ['S', 'T', 'A', 'C', 'K', 'O', 'V', 'E', 'R', 'F', 'L', 'O', 'W'];
// At position 3, delete 7 and add 7 elements: 
array1.splice(3, 7, "X","X","X","X","X","X","X");

console.log(array1);

Answer 3

One way is with Array.prototype.map:

This loops through every index of the array, and if the index is between 3 and 9 (inclusive), set it to 'X', otherwise keep it as the original chr (character)

var array1 = ['S', 'T', 'A', 'C', 'K', 'O', 'V', 'E', 'R', 'F', 'L', 'O', 'W'];

var array2 = array1.map((chr, idx) => 3 <= idx && idx <= 9 ? 'X' : chr);

console.log(array2);