Remove jquery as dependency and refactor the code

content.js

@@ -1,39 +1,37 @@
-var hidden_icon_name_html = "<input type='hidden' value='mata-inactive-38.png' id='mata-icon-name' />";
+var body = document.body;
+var isActive = false;
+var icon = document.createElement('input');
+    icon.type = 'hidden';
+    icon.value = 'meta-inactive-38.png';
+    icon.id = 'mata-icon-name';
 
-$("body").append(hidden_icon_name_html);
+body.appendChild(icon);
 
 function activate_mata() {
-  $("body").addClass("mata-friendly");
+  body.classList.add('mata-friendly');
+  icon.value = 'mata-active-38.png';
+  isActive = true;
 }
 
 function deactivate_mata() {
-  $("body").removeClass("mata-friendly");
+  body.classList.remove('mata-friendly');
+  icon.value = 'mata-inactive-38.png';
+  isActive = false;
 }
 
-chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
-  // Extension is clicked
-  if (request.message == "clicked_browser_action") {
-    // Change the extension's icon name on hidden field
-    if ($("#mata-icon-name").val() == "mata-inactive-38.png") {
-      $("#mata-icon-name").val("mata-active-38.png");
-
-      // Activate the mata
-      activate_mata();
-    } else {
-      $("#mata-icon-name").val("mata-inactive-38.png");
-
-      // Deactivate the mata
-      deactivate_mata();
-    }
-
-    chrome.runtime.sendMessage({ "message": "clicked_browser_action", "current_icon_path": $("#mata-icon-name").val() });
-  }
-});
-
-$("body").bind("DOMSubtreeModified", function() {
-  if ($("#mata-icon-name").val() == "mata-inactive-38.png") {
+function toggle_mata() {
+  if (isActive) {
     deactivate_mata();
   } else {
     activate_mata();
   }
+}
+
+chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
+  if (request.message == "clicked_browser_action") {
+    toggle_mata();
+    chrome.runtime.sendMessage({ "message": "clicked_browser_action", "current_icon_path": icon.value });
+  }
 });
+
+body.addEventListener("DOMSubtreeModified", toggle_mata);

manifest.json

@@ -3,7 +3,7 @@
 
   "name": "Mata",
   "description": "Reading the web should be friendly for your eyes",
-  "version": "1.0.0",
+  "version": "1.1.0",
 
   "icons": {
     "16": "mata-inactive-16.png",
@@ -25,7 +25,7 @@
         "<all_urls>"
       ],
       "css": ["content.css"],
-      "js": ["jquery-2.1.4.min.js", "content.js"]
+      "js": ["content.js"]
     }
   ]
 }