Función para enmascarar el personaje
<script>
// Function for masking the character
function MaskCharacter(str, mask, n = 1) {
// Slice the string and replace with
// mask then add remaining string
return ('' + str).slice(0, -n)
.replace(/./g, mask)
+ ('' + str).slice(-n);
}
// Number that we want to mask
var num = 12345678;
// Convert number into string
var str = num.toString();
// Call function without giving value of n
console.log(MaskCharacter(str, '#'));
// Call function with value of n
console.log(MaskCharacter(str, '#', 2));
</script>
Disgusted Dingo