How to slice a number in JavaScript?

change this :

var last = code.slice(-2);

to this :

var last = String(code).slice(-2);

or this :

var last = code.toString().slice(-2);

WHY?

because slice() is method of String not a Number. It extracts a section of a string and returns it as a new string, without modifying the original string.

UPDATE

based on the first comment.

var code = 130031;
var last = code.toString().slice(-2);
var n = [00, 01, 10, 11, 20, 21, 30, 31].includes(last);

For more information read about includes

If your root concern is creating a string without any quotes: here is a technique:

var x = String(/895804220010013030/);
x = x.substring(1, x.length-1);
x;

You can check the length to be confident about it.

From an older post's answer: Can you create a JavaScript string without using ' or " quotes?

EDIT:

Have to edit the start of the answer since I just realized that the number you're trying to capture in the code variable is actually greater than the max safe integer value available in JS.

slice is not a method defined on the Number type. You can choose to store the code as a string and that will make life easier for you,

var code = '895804220010013030';
var last = Number(code.slice(-2));
var n = [00, 01, 10, 11, 20, 21, 30, 31].includes(last);

if (n===true) {
  alert(n)
} else{
 alert('false')
}

Additionally, there are better ways to write the if-else since the value of n is going to be a boolean as includes will always return a true or false.

From MDN,

The includes() method determines whether an array includes a certain value among its entries, returning true or false as appropriate.

Either,

if (n) {
  alert(n);
} else {
  alert(false);
}

or simply,

alert(n);