Profile editing: Custom fields (deleting, editing) (#38066)

app/javascript/mastodon/utils/hash.test.ts

@@ -0,0 +1,48 @@
+import { describe, expect, it } from 'vitest';
+
+import { cyrb32, hashObjectArray } from './hash';
+
+describe('cyrb32', () => {
+  const input = 'mastodon';
+
+  it('returns a base-36 lowercase 1-6 character string', () => {
+    const hash = cyrb32(input);
+    expect(hash).toMatch(/^[0-9a-z]{1,6}$/);
+  });
+
+  it('returns the same output for same input and seed', () => {
+    const a = cyrb32(input, 1);
+    const b = cyrb32(input, 1);
+
+    expect(a).toBe(b);
+  });
+
+  it('produces different hashes for different seeds', () => {
+    const a = cyrb32(input, 1);
+    const b = cyrb32(input, 2);
+
+    expect(a).not.toBe(b);
+  });
+});
+
+describe('hashObjectArray', () => {
+  const input = [
+    { name: 'Alice', value: 'Developer' },
+    { name: 'Bob', value: 'Designer' },
+    { name: 'Alice', value: 'Developer' }, // Duplicate
+  ];
+
+  it('returns an array of the same length with unique hash keys', () => {
+    const result = hashObjectArray(input);
+    expect(result).toHaveLength(input.length);
+
+    const ids = result.map((obj) => obj.id);
+    const uniqueIds = new Set(ids);
+    expect(uniqueIds.size).toBe(ids.length);
+  });
+
+  it('allows custom key names for the hash', () => {
+    const result = hashObjectArray(input, 'hashKey');
+    expect(result[0]).toHaveProperty('hashKey');
+  });
+});

app/javascript/mastodon/utils/hash.ts

@@ -0,0 +1,39 @@
+/**
+ * Fast insecure hash function.
+ * @param str String to hash.
+ * @param seed Optional seed value for different hash outputs of the same string.
+ * @returns Base-36 hash (1-6 characters, typically 5-6).
+ */
+export function cyrb32(str: string, seed = 0) {
+  let h1 = 0xdeadbeef ^ seed;
+  for (let i = 0; i < str.length; i++) {
+    h1 = Math.imul(h1 ^ str.charCodeAt(i), 0x9e3779b1);
+  }
+  return ((h1 ^ (h1 >>> 16)) >>> 0).toString(36);
+}
+
+/**
+ * Hashes an array of objects into a new array where each object has a unique hash key.
+ * @param array Array of objects to hash.
+ * @param key Key name to use for the hash in the resulting objects (default: 'id').
+ */
+export function hashObjectArray<
+  TObj extends object,
+  TKey extends string = 'id',
+>(array: TObj[], key = 'id' as TKey): (TObj & Record<TKey, string>)[] {
+  const keySet = new Set<string>();
+
+  return array.map((obj) => {
+    const json = JSON.stringify(obj);
+    let seed = 0;
+    let hash = cyrb32(json, seed);
+    while (keySet.has(hash)) {
+      hash = cyrb32(json, ++seed);
+    }
+    keySet.add(hash);
+    return {
+      ...obj,
+      [key]: hash,
+    } as TObj & Record<TKey, string>;
+  });
+}