Improve performance of isEmojiOnlyText

ts/test-both/util/isEmojiOnlyText_test.ts

@@ -0,0 +1,28 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+
+import { isEmojiOnlyText } from '../../util/isEmojiOnlyText';
+
+describe('isEmojiOnlyText', () => {
+  it('returns false on empty string', () => {
+    assert.isFalse(isEmojiOnlyText(''));
+  });
+
+  it('returns false on non-emoji string', () => {
+    assert.isFalse(isEmojiOnlyText('123'));
+  });
+
+  it('returns false on mixed emoji/text string', () => {
+    assert.isFalse(isEmojiOnlyText('12😎3'));
+  });
+
+  it('returns false on mixed emoji/text string starting with emoji', () => {
+    assert.isFalse(isEmojiOnlyText('😎12😎3'));
+  });
+
+  it('returns true on all emoji string', () => {
+    assert.isTrue(isEmojiOnlyText('😎👍😀😮‍💨'));
+  });
+});

ts/util/isEmojiOnlyText.tsx

@@ -1,9 +1,22 @@
-// Copyright 2021 Signal Messenger, LLC
+// Copyright 2021-2022 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
-import * as grapheme from './grapheme';
-import { getEmojiCount } from '../components/emoji/lib';
+import emojiRegex from 'emoji-regex';
 
 export function isEmojiOnlyText(text: string): boolean {
-  return grapheme.count(text) === getEmojiCount(text);
+  if (text.length === 0) {
+    return false;
+  }
+
+  const regex = emojiRegex();
+  let len = 0;
+  for (const match of text.matchAll(regex)) {
+    // Skipped some non-emoji text, return early
+    if (match.index !== len) {
+      return false;
+    }
+
+    len += match[0].length;
+  }
+  return len === text.length;
 }