getting there

src/IndexedDBEngine.js

@@ -2,8 +2,8 @@ import { dbPromise, openDatabase } from './databaseLifecycle'
 import {
   DATA_VERSION_CURRENT,
   DB_NAME,
-  INDEX_GROUP_AND_ORDER,
-  KEY_VERSION,
+  INDEX_GROUP_AND_ORDER, INDEX_TOKENS,
+  KEY_VERSION, MODE_READONLY, MODE_READWRITE,
   STORE_EMOJI,
   STORE_META
 } from './constants'
@@ -19,11 +19,11 @@ export class IndexedDBEngine {
 
   async loadData (emojiBaseData) {
     const transformedData = transformEmojiBaseData(emojiBaseData)
-    const dataVersion = await dbPromise(this._db, STORE_META, 'readonly', (metaStore, cb) => {
+    const dataVersion = await dbPromise(this._db, STORE_META, MODE_READONLY, (metaStore, cb) => {
       metaStore.get(KEY_VERSION).onsuccess = e => cb(e.target.result)
     })
     if (dataVersion < DATA_VERSION_CURRENT) {
-      await dbPromise(this._db, [STORE_EMOJI, STORE_META], 'readwrite', ([emojiStore, metaStore]) => {
+      await dbPromise(this._db, [STORE_EMOJI, STORE_META], MODE_READWRITE, ([emojiStore, metaStore]) => {
         metaStore.get(KEY_VERSION).onsuccess = e => {
           const dataVersion = e.target.result
           // check again within the transaction to guard against concurrency, e.g. multiple browser tabs
@@ -38,11 +38,21 @@ export class IndexedDBEngine {
   }
 
   getEmojiByGroup (group) {
-    return dbPromise(this._db, STORE_EMOJI, 'readonly', (emojiStore, cb) => {
+    return dbPromise(this._db, STORE_EMOJI, MODE_READONLY, (emojiStore, cb) => {
       const range = IDBKeyRange.bound([group, 0], [group + 1, 0], false, true)
       emojiStore.index(INDEX_GROUP_AND_ORDER).getAll(range).onsuccess = e => {
         cb(e.target.result)
       }
     })
   }
+
+  searchEmojiByPrefix(prefix) {
+    prefix = prefix.toLowerCase()
+    return dbPromise(this._db, STORE_EMOJI, MODE_READONLY, (emojiStore, cb) => {
+      const range = IDBKeyRange.bound(prefix, prefix + '\uffff', false, true)
+      emojiStore.index(INDEX_TOKENS).getAll(range).onsuccess = e => {
+        cb(e.target.result)
+      }
+    })
+  }
 }

src/constants.js

@@ -6,8 +6,11 @@ export const DATA_VERSION_CURRENT = 2
 export const STORE_EMOJI = 'emoji'
 export const STORE_META = 'meta'
 export const FIELD_TOKENS = 'tokens'
+export const INDEX_TOKENS = 'tokens'
 export const FIELD_UNICODE = 'unicode'
 export const FIELD_GROUP = 'group'
 export const FIELD_ORDER = 'order'
 export const INDEX_GROUP_AND_ORDER = 'group-order'
 export const KEY_VERSION = 'version'
+export const MODE_READONLY = 'readonly'
+export const MODE_READWRITE= 'readwrite'

src/databaseLifecycle.js

@@ -1,4 +1,5 @@
-import { DB_VERSION_CURRENT, migrations } from './migrations'
+import { migrations } from './migrations'
+import { DB_VERSION_CURRENT } from './constants'
 
 const openReqs = {}
 const databaseCache = {}

src/index.js

@@ -1,6 +1,7 @@
-import { loadData, getEmojiByGroup } from './loadData'
+import { loadData, getEmojiByGroup, searchEmojiByPrefix } from './loadData'
 
 export {
   loadData,
-  getEmojiByGroup
+  getEmojiByGroup,
+  searchEmojiByPrefix
 }

src/loadData.js

@@ -21,3 +21,11 @@ export async function getEmojiByGroup (group) {
   await init()
   return idbEngine.getEmojiByGroup(group)
 }
+
+export async function searchEmojiByPrefix (prefix) {
+  if (typeof prefix !== 'string' || !prefix) {
+    throw new Error('expected a non-empty string, got: ' + prefix)
+  }
+  await init()
+  return idbEngine.searchEmojiByPrefix(prefix)
+}

src/migrations.js

@@ -5,7 +5,7 @@ import {
   INDEX_GROUP_AND_ORDER,
   KEY_VERSION,
   STORE_EMOJI,
-  STORE_META
+  STORE_META, INDEX_TOKENS
 } from './constants'
 
 function initialMigration (db, tx, done) {
@@ -14,19 +14,19 @@ function initialMigration (db, tx, done) {
       ? db.createObjectStore(name, init)
       : db.createObjectStore(name)
     if (indexes) {
-      Object.keys(indexes).forEach(indexKey => {
-        store.createIndex(indexKey, indexes[indexKey])
-      })
+      for (const { indexName, keyPath, multiEntry } of indexes) {
+        store.createIndex(indexName, keyPath, { multiEntry })
+      }
     }
     return store
   }
 
   const metaStore = createObjectStore(STORE_META)
   metaStore.put(DATA_VERSION_INITIAL, KEY_VERSION)
-  createObjectStore(STORE_EMOJI, { keyPath: FIELD_UNICODE }, {
-    [FIELD_TOKENS]: FIELD_TOKENS,
-    [INDEX_GROUP_AND_ORDER]: [FIELD_GROUP, FIELD_ORDER]
-  })
+  createObjectStore(STORE_EMOJI, { keyPath: FIELD_UNICODE }, [
+    { indexName: INDEX_TOKENS, keyPath: FIELD_TOKENS, multiEntry: true },
+    { indexName: INDEX_GROUP_AND_ORDER, keyPath: [FIELD_GROUP, FIELD_ORDER] }
+  ])
   done()
 }
 

test/index.html

@@ -7,12 +7,12 @@
 <body>
   <h1>Ad-hoc test</h1>
   <script type="module">
-      import { loadData, getEmojiByGroup } from '../pkg/dist-web/index.js'
+      import { loadData, getEmojiByGroup, searchEmojiByPrefix } from '../pkg/dist-web/index.js'
 
       (async () => {
         const emojiBaseData = await (await fetch('../node_modules/emojibase-data/en/compact.json')).json()
 
-        Object.assign(window, { loadData, getEmojiByGroup, emojiBaseData })
+        Object.assign(window, { loadData, getEmojiByGroup, emojiBaseData, searchEmojiByPrefix })
       })()
   </script>
 </body>