fix(trie): delete words containing supplementary Unicode characters

src/data-structures/trie/Trie.js

@@ -29,13 +29,15 @@ export default class Trie {
    * @return {Trie}
    */
   deleteWord(word) {
+    // Use the same code-point representation as addWord and lookup.
+    const characters = Array.from(word);
     const depthFirstDelete = (currentNode, charIndex = 0) => {
-      if (charIndex >= word.length) {
+      if (charIndex >= characters.length) {
         // Return if we're trying to delete the character that is out of word's scope.
         return;
       }
 
-      const character = word[charIndex];
+      const character = characters[charIndex];
       const nextNode = currentNode.getChild(character);
 
       if (nextNode == null) {
@@ -47,7 +49,7 @@ export default class Trie {
       depthFirstDelete(nextNode, charIndex + 1);
 
       // Since we're going to delete a word let's un-mark its last character isCompleteWord flag.
-      if (charIndex === (word.length - 1)) {
+      if (charIndex === (characters.length - 1)) {
         nextNode.isCompleteWord = false;
       }
 

src/data-structures/trie/__test__/Trie.test.js

@@ -62,6 +62,26 @@ describe('Trie', () => {
     expect(trie.doesWordExist('cart')).toBe(false);
   });
 
+  it('should delete words containing supplementary Unicode characters', () => {
+    const trie = new Trie();
+    const words = ['😀', '😀a', '😀b', 'a😀', 'a😀b', '𐐀'];
+    words.forEach((word) => trie.addWord(word));
+
+    expect(trie.deleteWord('😀c')).toBe(trie);
+    words.forEach((word) => expect(trie.doesWordExist(word)).toBe(true));
+
+    words.forEach((word, index) => {
+      expect(trie.deleteWord(word)).toBe(trie);
+      words.slice(0, index + 1).forEach((deleted) => {
+        expect(trie.doesWordExist(deleted)).toBe(false);
+      });
+      words.slice(index + 1).forEach((remaining) => {
+        expect(trie.doesWordExist(remaining)).toBe(true);
+      });
+    });
+    expect(trie.head.suggestChildren()).toEqual([]);
+  });
+
   it('should suggests next characters', () => {
     const trie = new Trie();