createSeededRng function exported

Last updated: 2026-03-05T10:53:28.864Z

Location

Metrics

LOC: 48 Complexity: 3 Params: 1

Signature

createSeededRng(seed: string): : SeededRng

Summary

Create a seeded PRNG instance. Returns a SeededRng object with utility methods that draw from the same deterministic sequence. ts const rng = createSeededRng("demo-seed-42"); rng.next(); // 0 ≤ n < 1 rng.int(1, 100); // 1 ≤ n ≤ 100 rng.pick(["a","b"]) // "a" or "b" deterministically

Source Code

export function createSeededRng(seed: string): SeededRng {
  let state = hashSeed(seed);

  /** mulberry32 core — returns float [0, 1) */
  function next(): number {
    state |= 0;
    state = (state + 0x6d2b79f5) | 0;
    let t = Math.imul(state ^ (state >>> 15), 1 | state);
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  }

  return {
    next,

    int(min: number, max: number): number {
      return Math.floor(next() * (max - min + 1)) + min;
    },

    pick<T>(array: readonly T[]): T {
      return array[Math.floor(next() * array.length)];
    },

    shuffle<T>(array: readonly T[]): T[] {
      const result = [...array];
      for (let i = result.length - 1; i > 0; i--) {
        const j = Math.floor(next() * (i + 1));
        [result[i], result[j]] = [result[j], result[i]];
      }
      return result;
    },

    char(charset: string): string {
      return charset[Math.floor(next() * charset.length)];
    },

    string(
      length: number,
      charset = "abcdefghijklmnopqrstuvwxyz0123456789",
    ): string {
      let result = "";
      for (let i = 0; i < length; i++) {
        result += charset[Math.floor(next() * charset.length)];
      }
      return result;
    },
  };
}

Members

Name	Kind	Visibility	Status	Signature
next	function		-	next(): : number

Dependencies (Outgoing)

graph LR createSeededRng["createSeededRng"] hashSeed["hashSeed"] createSeededRng -->|calls| hashSeed style createSeededRng fill:#dbeafe,stroke:#2563eb,stroke-width:2px click createSeededRng "71a63e2b315abc34.html" click hashSeed "692a3518abc2bb4b.html"

Target	Type
hashSeed	calls

Impact (Incoming)

graph LR createSeededRng["createSeededRng"] OrchestratorCallbacks["OrchestratorCallbacks"] start["start"] OrchestratorCallbacks -->|uses| createSeededRng start -->|calls| createSeededRng style createSeededRng fill:#dbeafe,stroke:#2563eb,stroke-width:2px click createSeededRng "71a63e2b315abc34.html" click OrchestratorCallbacks "984a6b93df2ea9af.html" click start "56469c2f243a2128.html"

Source	Type
OrchestratorCallbacks	uses
start	calls