2 files changed, 14 insertions, 0 deletions
diff --git a/ext/mixed/js/core.js b/ext/mixed/js/core.js
index 83813796..0e22b9ac 100644
--- a/ext/mixed/js/core.js
+++ b/ext/mixed/js/core.js
@@ -269,7 +269,11 @@ const yomichan = (() => {
         constructor() {
             super();
 
+            this._isBackendPreparedResolve = null;
+            this._isBackendPreparedPromise = new Promise((resolve) => (this._isBackendPreparedResolve = resolve));
+
             this._messageHandlers = new Map([
+                ['backendPrepared', this._onBackendPrepared.bind(this)],
                 ['getUrl', this._onMessageGetUrl.bind(this)],
                 ['optionsUpdated', this._onMessageOptionsUpdated.bind(this)],
                 ['zoomChanged', this._onMessageZoomChanged.bind(this)]
@@ -280,6 +284,11 @@ const yomichan = (() => {
 
         // Public
 
+        prepare() {
+            chrome.runtime.sendMessage({action: 'yomichanCoreReady'});
+            return this._isBackendPreparedPromise;
+        }
+
         generateId(length) {
             const array = new Uint8Array(length);
             window.crypto.getRandomValues(array);
@@ -305,6 +314,10 @@ const yomichan = (() => {
             return false;
         }
 
+        _onBackendPrepared() {
+            this._isBackendPreparedResolve();
+        }
+
         _onMessageGetUrl() {
             return {url: window.location.href};
         }
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index e3e5e7df..6a762a65 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -153,6 +153,7 @@ class Display {
     }
 
     async prepare(options=null) {
+        await yomichan.prepare();
         const displayGeneratorPromise = this.displayGenerator.prepare();
         const updateOptionsPromise = this.updateOptions(options);
         await Promise.all([displayGeneratorPromise, updateOptionsPromise]);