Hi,
Bei mozilla.org steht zu Math.random() Folgendes:
"Returns a number value with positive sign, greater than or equal to 0 but less than 1, chosen randomly or pseudorandomly with approximately uniform distribution over that range, using an implementation-dependent algorithm or strategy."
Also 0 <= Math.random() < 1, genau wie wahrscheinlich in jeder anderen Sprache auch.
Gruß
Steffen