What I'm Learning Today: parseInt() and Random Number Generator with user-defined parameters

The second full programming assignment I did in the Treehouse JS track was a random number generator, where the user provides two numbers that define the range of possible numbers returned. I liked this challenge because there are so many complications that you have to think about when dealing with user inputs. Like, what if the user submits the same number twice? Or what if they enter something crazy? Here's what I came up with:

// collect 2 numbers from user
// print a random whole number that falls between these two numbers
// TODO: deal with non-number inputs

// collect num1
var num1 = parseInt(prompt("Give me a number!"));

// collect num2
var num2 = parseInt(prompt("Give me a different number!"));
// do not accept num2 if it is equal to num1
  num2 = parseInt(prompt("Give me a DIFFERENT number!")); 
// build a func to subtract the smaller num from the larger num
var range = function(a,b){
  if(b>a) {
    return b-a;
  else { return a-b; }
// invoke the range function on num1 and num2 
var rangeOfNums = range(num1,num2);

// use Math methods to generate random num 
// store in variable to return to user
var randomNum = Math.floor(Math.random()*rangeOfNums) +1;

// alert the randomNum to user
alert("Your number is " + randomNum);