reset reply context state when URL is removed

controllers/controllers.php

@@ -397,6 +397,10 @@ $app->get('/reply/preview', function() use($app) {
   if($user=require_login($app)) {
     $params = $app->request()->params();
 
+    if(!isset($params['url']) || !$params['url']) {
+      return '';
+    }
+
     $reply_url = trim($params['url']);
 
     if(preg_match('/twtr\.io\/([0-9a-z]+)/i', $reply_url, $match)) {

views/new-post.php

@@ -310,6 +310,14 @@ $(function(){
 
   $("#note_in_reply_to").on('change', function(){
     var reply_to = $("#note_in_reply_to").val();
+
+    if(reply_to == "") {
+      $(".reply-section").addClass("hidden");
+      $(".reply-context").addClass("hidden");
+      $("#expand-reply").removeClass("hidden");
+      return;
+    }
+
     $(".reply-section .loading").removeClass("hidden");
     $.get("/reply/preview", {url:reply_to}, function(data){