reorganize js callbacks and startup sequence

javascript/promptChecker.js

@@ -3,8 +3,6 @@
 // Counts open and closed brackets (round, square, curly) in the prompt and negative prompt text boxes in the txt2img and img2img tabs.
 // If there's a mismatch, the keyword counter turns red and if you hover on it, a tooltip tells you what's wrong.
 
-let promptCheckerInitialized = false;
-
 function checkBrackets(textArea, counterElt) {
   const counts = {};
   const errors = [];
@@ -25,17 +23,15 @@ function setupBracketChecking(idPrompt, idCounter) {
   const textarea = gradioApp().querySelector(`#${idPrompt} > label > textarea`);
   const counter = gradioApp().getElementById(idCounter);
   if (!textarea || !counter) return;
-  if (!promptCheckerInitialized) log('initPromptChecker');
-  promptCheckerInitialized = true;
   textarea.addEventListener('input', () => checkBrackets(textarea, counter));
 }
 
-onAfterUiUpdate(() => {
-  if (promptCheckerInitialized) return;
+async function initPromptChecker() {
+  log('initPromptChecker');
   setupBracketChecking('txt2img_prompt', 'txt2img_token_counter');
   setupBracketChecking('txt2img_neg_prompt', 'txt2img_negative_token_counter');
   setupBracketChecking('img2img_prompt', 'img2img_token_counter');
   setupBracketChecking('img2img_neg_prompt', 'img2img_negative_token_counter');
   setupBracketChecking('control_prompt', 'control_token_counter');
   setupBracketChecking('control_neg_prompt', 'control_negative_token_counter');
-});
+}