feat!: high precision random number generator (#2357)

4 files changed, 32 insertions, 7 deletions

diff --git a/src/faker.ts b/src/faker.ts
index c4f65187..5f5e14ce 100644
--- a/src/faker.ts
+++ b/src/faker.ts
@@ -152,7 +152,7 @@ export class Faker extends SimpleFaker {
      * Specify this only if you want to use it to achieve a specific goal,
      * such as sharing the same random generator with other instances/tools.
      *
-     * @default generateMersenne32Randomizer()
+     * @default generateMersenne53Randomizer()
      */
     randomizer?: Randomizer;
   }) {
diff --git a/src/index.ts b/src/index.ts
index 4fb24bc4..33ec9e2e 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -72,6 +72,10 @@ export type {
 export { FakerError } from './errors/faker-error';
 export { Faker } from './faker';
 export type { FakerOptions } from './faker';
+export {
+  generateMersenne32Randomizer,
+  generateMersenne53Randomizer,
+} from './internal/mersenne';
 export * from './locale';
 export { fakerEN as faker } from './locale';
 export * from './locales';
diff --git a/src/internal/mersenne.ts b/src/internal/mersenne.ts
index 2372e364..d01b5ee9 100644
--- a/src/internal/mersenne.ts
+++ b/src/internal/mersenne.ts
@@ -328,9 +328,7 @@ export class MersenneTwister19937 {
 
 /**
  * Generates a MersenneTwister19937 randomizer with 32 bits of precision.
- * This is the default randomizer used by Faker.
- *
- * @internal
+ * This is the default randomizer used by faker prior to v9.0.
  */
 export function generateMersenne32Randomizer(): Randomizer {
   const twister = new MersenneTwister19937();
@@ -350,3 +348,26 @@ export function generateMersenne32Randomizer(): Randomizer {
     },
   };
 }
+
+/**
+ * Generates a MersenneTwister19937 randomizer with 53 bits of precision.
+ * This is the default randomizer used by faker starting with v9.0.
+ */
+export function generateMersenne53Randomizer(): Randomizer {
+  const twister = new MersenneTwister19937();
+
+  twister.initGenrand(Math.ceil(Math.random() * Number.MAX_SAFE_INTEGER));
+
+  return {
+    next(): number {
+      return twister.genrandRes53();
+    },
+    seed(seed: number | number[]): void {
+      if (typeof seed === 'number') {
+        twister.initGenrand(seed);
+      } else if (Array.isArray(seed)) {
+        twister.initByArray(seed, seed.length);
+      }
+    },
+  };
+}
diff --git a/src/simple-faker.ts b/src/simple-faker.ts
index 3993392d..e775cbc7 100644
--- a/src/simple-faker.ts
+++ b/src/simple-faker.ts
@@ -1,4 +1,4 @@
-import { generateMersenne32Randomizer } from './internal/mersenne';
+import { generateMersenne53Randomizer } from './internal/mersenne';
 import { DatatypeModule } from './modules/datatype';
 import { SimpleDateModule } from './modules/date';
 import { SimpleHelpersModule } from './modules/helpers';
@@ -117,12 +117,12 @@ export class SimpleFaker {
        * Specify this only if you want to use it to achieve a specific goal,
        * such as sharing the same random generator with other instances/tools.
        *
-       * @default generateMersenne32Randomizer()
+       * @default generateMersenne53Randomizer()
        */
       randomizer?: Randomizer;
     } = {}
   ) {
-    const { randomizer = generateMersenne32Randomizer() } = options;
+    const { randomizer = generateMersenne53Randomizer() } = options;
 
     this._randomizer = randomizer;
   }