feat(utils): stringToIntegerInRange

packages/utils/src/getIntegerInRangeFromString.ts

@@ -0,0 +1,26 @@
+/**
+ *
+ * @param input - any string
+ * @param max - max number not included for the range, if 100 is provided the range will be 0 to 99, if 101, then range is 0 to 100
+ * @returns number
+ * @see https://stackoverflow.com/questions/6122571/simple-non-secure-hash-function-for-javascript
+ */
+export const getIntegerInRangeFromString = (input: string, max: number): number => {
+    let hash = 0;
+    if (input.length === 0) {
+        return 0;
+    }
+
+    // Non secure but fash hash function with browser compatibility
+    // https://stackoverflow.com/questions/6122571/simple-non-secure-hash-function-for-javascript
+    for (let i = 0; i < input.length; i++) {
+        const char = input.charCodeAt(i);
+        hash = (hash << 5) - hash + char;
+        // Convert to 32bit integer.
+        hash |= 0;
+    }
+
+    // The result of `x % n` is always in the range `-(n-1)` to `n-1`.
+    // Taking the absolute value ensures it's in the range 0 to max.
+    return Math.abs(hash % max);
+};

packages/utils/src/index.ts

@@ -58,3 +58,4 @@ export * from './typedObjectKeys';
 export * from './urlToOnion';
 export * from './zip';
 export * from './removeTrailingSlashes';
+export * from './getIntegerInRangeFromString';

packages/utils/tests/getIntegerInRangeFromString.test.ts

@@ -0,0 +1,33 @@
+import { getIntegerInRangeFromString } from '../src/getIntegerInRangeFromString';
+
+describe('getIntegerInRangeFromString', () => {
+    it('should always produce the same number for the same string input', () => {
+        const input = '47A2176AC04E609FD0E9811A';
+        const result1 = getIntegerInRangeFromString(input, 101);
+        const result2 = getIntegerInRangeFromString(input, 101);
+        expect(result1).toEqual(result2);
+    });
+
+    it('should always be deterministic in producing a number from same input', () => {
+        const input = 'z';
+        const result1 = getIntegerInRangeFromString(input, 101);
+        expect(result1).toBe(21);
+    });
+
+    it('should return a number between 0 and 100 for various inputs', () => {
+        const inputs = [
+            'z',
+            '', // It should work with empty string as well.
+            'a-much-longer-string-to-test-just-to-test-that-something-like-this-will-also-work',
+            '47A2176AC04E609FD0E9811A',
+            '!@#$%^&*()-and-some-other-characters-ěščřžýáíé',
+            'another-device-id-456',
+        ];
+
+        inputs.forEach(input => {
+            const result = getIntegerInRangeFromString(input, 101);
+            expect(result).toBeGreaterThanOrEqual(0);
+            expect(result).toBeLessThan(101);
+        });
+    });
+});