jQuery is undefined in chrome extension?
<p>I am trying to run a simple jQuery call in a js file while making my first chrome extension but not sure why I keep getting this error:</p>

<pre><code>Uncaught ReferenceError: $ is not defined
</code></pre>

<p>Here is my manifest file:</p>

<pre><code>{
  "manifest_version": 2,
  "name": "Getting started example",
  "version": "1.0",

"description": "This extension shows a Google Image search result for the current page",

 "background": {
    "scripts": ["jquery-2.2.0.min.js", "popup.js"],
     "persistent": false
  },

  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Click here!"
  },
  "permissions": [
    "activeTab",
    "https://ajax.googleapis.com/"
  ]
}
</code></pre>

<p>Here is the onclick call in popup js:</p>

<pre><code>chrome.browserAction.onClicked.addListener(function(tab) {
  console.log("FIRE");
  chrome.tabs.executeScript(null, {file: "testScript.js"});
});
</code></pre>

<p>Here is the test script where the error shows:</p>

<pre><code>console.log('foo'); 
console.log($('#page-top'));
</code></pre>

<p>foo gets printed but then I get the error on $</p>