title: Avoid dynamically injecting the same script multiple times when using chrome.tabs.executeScript(...)
body: <p>I'm building a Google Chrome extension.  The basic setup is I have a Browser action button that injects jQuery and another bit of JavaScript into the active tab when it is clicked to do it's thing.  </p>
  
  <p>This is my first Chrome extension, but it seems like if the user clicks the button to take action a second time the scripts will be re-injected.  This is a problem because the main pages this is going to work with are all AJAX, so the page content changes significantly but the actual page URL never changes.</p>
  
  <p>Is this a legitimate concern, or am I over thinking it and is there a simple way to prevent the scripts from being injected multiple times into the same page?  Should I perhaps be specifying these as content scripts instead?</p>