Help me why my js code doesn't work?

Question

function maskify(cc) {
let arr = cc.split('');
arr.splice(-1,4);
return arr
}

Comments

I need to remove the last 4 elements.

Answer 1

The string also has a slice:

function maskify(cc) {
  return cc.slice(0, -4);
}

If you need an array on the output:

function maskify(cc) {
  return cc.slice(0, -4).split('');
}

Answer 2

What's with all the array and splice stuff? There is a substr:
https://developer.mozilla.org/ru/docs/Web/JavaScri...

Answer 3

let a = [1,2,3,4,5,6]
a.reverse().slice(4).reverse()