Small bug; your code has a small bias for right. if (random > 0.5) { direction = 'right'; } 1 is not included in Math.Random, so it should be < 0.5 == lef

Small bug; your code has a small bias for right. if (random > 0.5) { direction = 'right'; } 1 is not included in Math.Random, so it should be < 0.5 == left, >= 0.5 == right.