i had seen about puzzlescript and it was html5 libraries. So i do have a bit knowledge about html5. Basically you need to use Math.floor() to round up the Math.Random() so the codes it looks like this
Math.random() //<< it returns double number from 0 - 1. example 0.189281, 0.83823, 0.90823879, 0.49874965
Math.floor(Math.random() * 10); //<< return a number 0 - 9
function getRndInteger(min, max) {
return Math.floor(Math.random() * (max - min + 1) ) + min;
} //<< this return an int number with threshold
i found it at this place