diff --git a/online-editor.js b/online-editor.js
index dac18c9..28f5239 100644
--- a/online-editor.js
+++ b/online-editor.js
@@ -152,13 +152,13 @@ async function besProof(el) {
 function besHandleBeforeInput(editorId, event) {
   let editor = besEditors[editorId]
   if (editor.timer) clearTimeout(editor.timer)
+  let edit = document.getElementById(editorId)
   editor.timer = setTimeout(function () {
     besProof(edit)
   }, 1000)
 
   // No need to invalidate elements after range.startContainer since they will
   // get either deleted or replaced.
-  let edit = document.getElementById(editorId)
   event
     .getTargetRanges()
     .forEach(range =>