SeedRandom

Seeded random number generator to get reproducible sequences of values.

SeedRandom provides a deterministic pseudo-random number generator that produces the same sequence of random values for a given seed. This is essential for:

• Procedural generation that needs to be reproducible
• Multiplayer games requiring synchronized random events
• Testing scenarios that need predictable randomness
• Save/load systems that need to recreate random sequences

The implementation uses the Park Miller (1988) "minimal standard" linear congruential generator algorithm: (seed * 16807) % 2147483647

Example usage:

// Create a seeded random generator
var rng = new SeedRandom(12345);

// Generate random values
var randomFloat = rng.random();           // [0, 1)
var randomInt = rng.between(1, 100);      // [1, 100)

// Shuffle an array deterministically
var items = [1, 2, 3, 4, 5];
rng.shuffle(items);

// Reset to initial seed to replay sequence
rng.reset();
var sameFloat = rng.random(); // Same as first randomFloat

Note: This is not cryptographically secure and should not be used for security-sensitive applications.

Instance Members #

The current seed value. This value changes with each random number generation.

The initial seed value used when creating this generator. Used by reset() to restore the original sequence.

Shuffle an Array in place using the Fisher-Yates algorithm.

This operation modifies the original array. The shuffle is deterministic based on the current seed state, so the same seed will always produce the same shuffle order.

Example:

var deck = ["A", "K", "Q", "J", "10", "9", "8", "7"];
rng.shuffle(deck);
// deck is now shuffled in a reproducible way

Returns a pseudo-random float in the range [0, 1).

The value is uniformly distributed and will be >= 0 and < 1. Each call advances the internal seed state.

Returns a pseudo-random integer in the range [min, max).

The value will be >= min and < max. The distribution is uniform across the range.

Example:

var diceRoll = rng.between(1, 7);    // 1-6
var percent = rng.between(0, 101);   // 0-100

Resets the generator to its initial seed value.

This allows replaying the same sequence of random values. Optionally, a new initial seed can be provided.

Example:

var rng = new SeedRandom(100);
var a = rng.random();
var b = rng.random();

rng.reset();           // Back to seed 100
var a2 = rng.random(); // Same as 'a'
var b2 = rng.random(); // Same as 'b'

rng.reset(200);        // Change to new seed

Creates a new seeded random number generator.