JavaScript rounding/random numbers

javascript_random_round.js

// declare our variables
var r, random, max = 20;

// get a random number between 0 (inclusive) and 1 (exclusive)
r = Math.random();

console.log(r);

// get a random number less than the maximum
random = max * r;

console.log(random);

// round the random number in a few ways
console.log(Math.round(random));
console.log(Math.ceil(random));
console.log(Math.floor(random));

// get the integer value of our random number, adding 1 to make sure we can hit the upper bound (20)
random = Math.floor(random + 1);

console.log(random);