title: automaticlly running your JavaScript against someone else's site (in your browser only)
body: <p>I've written some custom analytics JS code.  Nothing too fancy, mostly for learning purposes. </p>
  
  <p>Now I'm testing it against sites that I have no server level access to like banks, airlines, etc. of course running in my browser only.   I'm just copying and pasting the code in console, the having the script output the collected analytics data to the console.  </p>
  
  <p>Its getting annoying copying and pasting, and having to redo it when i navigate to a new page, site, etc.  Is there a way to get Firefox or Chrome to automatically inject my script in to any site i visit.  Does anyone know of a tool that does this, plugin or extension?  I suppose i could try to write an extension myself but figured i'd ask to see if anyone knows of any existing tools to do such a thing.</p>
  
  <p>thanks in advance </p>