Add getTitleText method

src/RichTextEditor.js

             }
           }
           break;
+        case messages.TITLE_TEXT_RESPONSE:
+          if (this.titleTextResolve) {
+            this.titleTextResolve(message.data);
+            this.titleTextResolve = undefined;
+            this.titleTextReject = undefined;
+            if (this.pendingTitleText) {
+              clearTimeout(this.pendingTitleText);
+              this.pendingTitleText = undefined;
+            }
+          }
+          break;
         case messages.CONTENT_HTML_RESPONSE:
           if (this.contentResolve) {
             this.contentResolve(message.data);
     });
   }
 
+  async getTitleText() {
+    return new Promise((resolve, reject) => {
+      this.titleTextResolve = resolve;
+      this.titleTextReject = reject;
+      this._sendAction(actions.getTitleText);
+
+      this.pendingTitleText = setTimeout(() => {
+        if (this.titleTextReject) {
+          this.titleTextReject('timeout');
+        }
+      }, 5000);
+    });
+  }
+
   async getContentHtml() {
     return new Promise((resolve, reject) => {
       this.contentResolve = resolve;

src/WebviewMessageHandler.js

           var html = zss_editor.getTitleHTML();
           WebViewBridge.send(JSON.stringify({type: '${messages.TITLE_HTML_RESPONSE}', data: html}));
           break;
+        case '${actions.getTitleText}':
+          var html = zss_editor.getTitleText();
+          WebViewBridge.send(JSON.stringify({type: '${messages.TITLE_TEXT_RESPONSE}', data: html}));
+          break;
         case '${actions.getContentHtml}':
           var html = zss_editor.getContentHTML();
           WebViewBridge.send(JSON.stringify({type: '${messages.CONTENT_HTML_RESPONSE}', data: html}));

src/const.js

   setTitleHtml: 'SET_TITLE_HTML',
   setContentHtml: 'SET_CONTENT_HTML',
   getTitleHtml: 'GET_TITLE_HTML',
+  getTitleText: 'GET_TITLE_TEXT',
   getContentHtml: 'GET_CONTENT_HTML',
   blurTitleEditor: 'BLUR_TITLE_EDITOR',
   blurContentEditor: 'BLUR_CONTENT_EDITOR',
 
 export const messages = {
   TITLE_HTML_RESPONSE: 'TITLE_HTML_RESPONSE',
+  TITLE_TEXT_RESPONSE: 'TITLE_TEXT_RESPONSE',
   CONTENT_HTML_RESPONSE: 'CONTENT_HTML_RESPONSE',
   ZSS_INITIALIZED: 'ZSS_INITIALIZED',
   SCROLL: 'SCROLL',