--- a/tweetdeck-large-image.user.js	Thu Apr 15 14:56:23 2021 +0900
+++ b/tweetdeck-large-image.user.js	Thu Apr 15 15:01:22 2021 +0900
@@ -12,26 +12,7 @@
 ;(function () {
   'use strict'
 
-  // loop through passed nodes (or body if called without arguments)
-  var run = function (nodes) {
-    if (nodes == null) {
-      nodes = [document.body]
-    }
-
-    for (var i = 0; i < nodes.length; i++) {
-      // first try fixing itself
-      fix(nodes[i])
-
-      // and then find all the links inside
-      var links = nodes[i].querySelectorAll('.js-media-image-link')
-
-      for (var j = 0; j < links.length; j++) {
-        fix(links[j])
-      }
-    }
-  }
-
-  var fix = function (link) {
+  const fix = function (link) {
     // basic sanity check
     if (!link.classList.contains('js-media-image-link')) {
       return
@@ -43,8 +24,8 @@
     }
     link._ecUserscript = true
 
-    var image = link.querySelector('.media-img')
-    var url
+    const image = link.querySelector('.media-img')
+    let url
 
     // sometimes the image is just background image of the link.
     // strip all query strings and original :size suffix
@@ -54,7 +35,7 @@
       url = image.src
     }
 
-    var parsedUrl = new URL(url)
+    const parsedUrl = new URL(url)
 
     if (parsedUrl.searchParams.get('name') == null) {
       url = url.replace(/(\..+:).+/, '$1orig')
@@ -69,14 +50,33 @@
     link.setAttribute('href', url)
   }
 
-  var onMutate = function (mutations) {
-    for (var mutation in mutations) {
+  // loop through passed nodes (or body if called without arguments)
+  const run = function (nodes) {
+    if (nodes == null) {
+      nodes = [document.body]
+    }
+
+    for (let i = 0; i < nodes.length; i++) {
+      // first try fixing itself
+      fix(nodes[i])
+
+      // and then find all the links inside
+      const links = nodes[i].querySelectorAll('.js-media-image-link')
+
+      for (let j = 0; j < links.length; j++) {
+        fix(links[j])
+      }
+    }
+  }
+
+  const onMutate = function (mutations) {
+    for (const mutation in mutations) {
       run(mutation.addedNodes)
     }
   }
 
   // the observer
-  var observer = new window.MutationObserver(onMutate)
+  const observer = new window.MutationObserver(onMutate)
 
   // start the observer
   observer.observe(document, { childList: true, subtree: true })