The random package provides several functions for generating random numbers. It uses a cryptographically strong pseudorandom number generator when possible, but falls back to a weaker random number generator when cryptographically strong randomness is not available (on older browsers or on servers that don't have enough entropy to seed the cryptographically strong generator).

Random.id([n]) - Returns a unique identifier, such as "Jjwjg6gouWLXhMGKW", that is likely to be unique in the whole world. The optional argument n specifies the length of the identifier in characters and defaults to 17.
Random.secret([n]) - Returns a random string of printable characters with 6 bits of entropy per character. The optional argument n specifies the length of the secret string and defaults to 43 characters, or 256 bits of entropy. Use Random.secret for security-critical secrets that are intended for machine, rather than human, consumption.
Random.fraction() - Returns a number between 0 and 1, like Math.random.
Random.choice(arrayOrString) - Returns a random element of the given array or string.
Random.hexString(n) - Returns a random string of n hexadecimal digits.