diff --git a/web/pdf_find_bar.js b/web/pdf_find_bar.js
index 35962b25c..812949d65 100644
--- a/web/pdf_find_bar.js
+++ b/web/pdf_find_bar.js
@@ -22,9 +22,10 @@ import { mozL10n } from './ui_utils';
  * also sets up the appropriate events for the controls. Actual searching
  * is done by PDFFindController.
  */
-var PDFFindBar = (function PDFFindBarClosure() {
-  function PDFFindBar(options) {
+class PDFFindBar {
+  constructor(options) {
     this.opened = false;
+
     this.bar = options.bar || null;
     this.toggleButton = options.toggleButton || null;
     this.findField = options.findField || null;
@@ -44,182 +45,175 @@ var PDFFindBar = (function PDFFindBarClosure() {
     }
 
     // Add event listeners to the DOM elements.
-    var self = this;
-    this.toggleButton.addEventListener('click', function() {
-      self.toggle();
+    this.toggleButton.addEventListener('click', () => {
+      this.toggle();
     });
 
-    this.findField.addEventListener('input', function() {
-      self.dispatchEvent('');
+    this.findField.addEventListener('input', () => {
+      this.dispatchEvent('');
     });
 
-    this.bar.addEventListener('keydown', function(evt) {
-      switch (evt.keyCode) {
+    this.bar.addEventListener('keydown', (e) => {
+      switch (e.keyCode) {
         case 13: // Enter
-          if (evt.target === self.findField) {
-            self.dispatchEvent('again', evt.shiftKey);
+          if (e.target === this.findField) {
+            this.dispatchEvent('again', e.shiftKey);
           }
           break;
         case 27: // Escape
-          self.close();
+          this.close();
           break;
       }
     });
 
-    this.findPreviousButton.addEventListener('click', function() {
-      self.dispatchEvent('again', true);
+    this.findPreviousButton.addEventListener('click', () => {
+      this.dispatchEvent('again', true);
     });
 
-    this.findNextButton.addEventListener('click', function() {
-      self.dispatchEvent('again', false);
+    this.findNextButton.addEventListener('click', () => {
+      this.dispatchEvent('again', false);
     });
 
-    this.highlightAll.addEventListener('click', function() {
-      self.dispatchEvent('highlightallchange');
+    this.highlightAll.addEventListener('click', () => {
+      this.dispatchEvent('highlightallchange');
     });
 
-    this.caseSensitive.addEventListener('click', function() {
-      self.dispatchEvent('casesensitivitychange');
+    this.caseSensitive.addEventListener('click', () => {
+      this.dispatchEvent('casesensitivitychange');
     });
 
     this.eventBus.on('resize', this._adjustWidth.bind(this));
   }
 
-  PDFFindBar.prototype = {
-    reset: function PDFFindBar_reset() {
-      this.updateUIState();
-    },
+  reset() {
+    this.updateUIState();
+  }
 
-    dispatchEvent: function PDFFindBar_dispatchEvent(type, findPrev) {
-      this.eventBus.dispatch('find', {
-        source: this,
-        type: type,
-        query: this.findField.value,
-        caseSensitive: this.caseSensitive.checked,
-        phraseSearch: true,
-        highlightAll: this.highlightAll.checked,
-        findPrevious: findPrev
-      });
-    },
+  dispatchEvent(type, findPrev) {
+    this.eventBus.dispatch('find', {
+      source: this,
+      type,
+      query: this.findField.value,
+      caseSensitive: this.caseSensitive.checked,
+      phraseSearch: true,
+      highlightAll: this.highlightAll.checked,
+      findPrevious: findPrev,
+    });
+  }
 
-    updateUIState:
-        function PDFFindBar_updateUIState(state, previous, matchCount) {
-      var notFound = false;
-      var findMsg = '';
-      var status = '';
+  updateUIState(state, previous, matchCount) {
+    var notFound = false;
+    var findMsg = '';
+    var status = '';
 
-      switch (state) {
-        case FindStates.FIND_FOUND:
-          break;
+    switch (state) {
+      case FindStates.FIND_FOUND:
+        break;
 
-        case FindStates.FIND_PENDING:
-          status = 'pending';
-          break;
+      case FindStates.FIND_PENDING:
+        status = 'pending';
+        break;
 
-        case FindStates.FIND_NOTFOUND:
-          findMsg = mozL10n.get('find_not_found', null, 'Phrase not found');
-          notFound = true;
-          break;
+      case FindStates.FIND_NOTFOUND:
+        findMsg = mozL10n.get('find_not_found', null, 'Phrase not found');
+        notFound = true;
+        break;
 
-        case FindStates.FIND_WRAPPED:
-          if (previous) {
-            findMsg = mozL10n.get('find_reached_top', null,
-              'Reached top of document, continued from bottom');
-          } else {
-            findMsg = mozL10n.get('find_reached_bottom', null,
-              'Reached end of document, continued from top');
-          }
-          break;
-      }
+      case FindStates.FIND_WRAPPED:
+        if (previous) {
+          findMsg = mozL10n.get('find_reached_top', null,
+            'Reached top of document, continued from bottom');
+        } else {
+          findMsg = mozL10n.get('find_reached_bottom', null,
+            'Reached end of document, continued from top');
+        }
+        break;
+    }
 
-      if (notFound) {
-        this.findField.classList.add('notFound');
-      } else {
-        this.findField.classList.remove('notFound');
-      }
+    if (notFound) {
+      this.findField.classList.add('notFound');
+    } else {
+      this.findField.classList.remove('notFound');
+    }
 
-      this.findField.setAttribute('data-status', status);
-      this.findMsg.textContent = findMsg;
+    this.findField.setAttribute('data-status', status);
+    this.findMsg.textContent = findMsg;
 
-      this.updateResultsCount(matchCount);
-      this._adjustWidth();
-    },
+    this.updateResultsCount(matchCount);
+    this._adjustWidth();
+  }
 
-    updateResultsCount: function(matchCount) {
-      if (!this.findResultsCount) {
-        return; // no UI control is provided
-      }
+  updateResultsCount(matchCount) {
+    if (!this.findResultsCount) {
+      return; // No UI control is provided.
+    }
 
-      // If there are no matches, hide the counter
-      if (!matchCount) {
-        this.findResultsCount.classList.add('hidden');
-        return;
-      }
+    // If there are no matches, hide the counter.
+    if (!matchCount) {
+      this.findResultsCount.classList.add('hidden');
+      return;
+    }
 
-      // Create the match counter
-      this.findResultsCount.textContent = matchCount.toLocaleString();
+    // Create and show the match counter.
+    this.findResultsCount.textContent = matchCount.toLocaleString();
+    this.findResultsCount.classList.remove('hidden');
+  }
 
-      // Show the counter
-      this.findResultsCount.classList.remove('hidden');
-    },
+  open() {
+    if (!this.opened) {
+      this.opened = true;
+      this.toggleButton.classList.add('toggled');
+      this.bar.classList.remove('hidden');
+    }
+    this.findField.select();
+    this.findField.focus();
 
-    open: function PDFFindBar_open() {
-      if (!this.opened) {
-        this.opened = true;
-        this.toggleButton.classList.add('toggled');
-        this.bar.classList.remove('hidden');
-      }
-      this.findField.select();
-      this.findField.focus();
+    this._adjustWidth();
+  }
 
-      this._adjustWidth();
-    },
+  close() {
+    if (!this.opened) {
+      return;
+    }
+    this.opened = false;
+    this.toggleButton.classList.remove('toggled');
+    this.bar.classList.add('hidden');
+    this.findController.active = false;
+  }
 
-    close: function PDFFindBar_close() {
-      if (!this.opened) {
-        return;
-      }
-      this.opened = false;
-      this.toggleButton.classList.remove('toggled');
-      this.bar.classList.add('hidden');
-      this.findController.active = false;
-    },
+  toggle() {
+    if (this.opened) {
+      this.close();
+    } else {
+      this.open();
+    }
+  }
 
-    toggle: function PDFFindBar_toggle() {
-      if (this.opened) {
-        this.close();
-      } else {
-        this.open();
-      }
-    },
+  /**
+   * @private
+   */
+  _adjustWidth() {
+    if (!this.opened) {
+      return;
+    }
 
-    /**
-     * @private
-     */
-    _adjustWidth: function PDFFindBar_adjustWidth() {
-      if (!this.opened) {
-        return;
-      }
+    // The find bar has an absolute position and thus the browser extends
+    // its width to the maximum possible width once the find bar does not fit
+    // entirely within the window anymore (and its elements are automatically
+    // wrapped). Here we detect and fix that.
+    this.bar.classList.remove('wrapContainers');
 
-      // The find bar has an absolute position and thus the browser extends
-      // its width to the maximum possible width once the find bar does not fit
-      // entirely within the window anymore (and its elements are automatically
-      // wrapped). Here we detect and fix that.
-      this.bar.classList.remove('wrapContainers');
+    var findbarHeight = this.bar.clientHeight;
+    var inputContainerHeight = this.bar.firstElementChild.clientHeight;
 
-      var findbarHeight = this.bar.clientHeight;
-      var inputContainerHeight = this.bar.firstElementChild.clientHeight;
-
-      if (findbarHeight > inputContainerHeight) {
-        // The findbar is taller than the input container, which means that
-        // the browser wrapped some of the elements. For a consistent look,
-        // wrap all of them to adjust the width of the find bar.
-        this.bar.classList.add('wrapContainers');
-      }
-    },
-  };
-  return PDFFindBar;
-})();
+    if (findbarHeight > inputContainerHeight) {
+      // The findbar is taller than the input container, which means that
+      // the browser wrapped some of the elements. For a consistent look,
+      // wrap all of them to adjust the width of the find bar.
+      this.bar.classList.add('wrapContainers');
+    }
+  }
+}
 
 export {
   PDFFindBar,