title: How do I tell which javascript framework is validating forms on a website
body: <p>I am trying to build a chrome extension to enter data into online forms on sites like toysrus.com and macys.com.  A chrome extension can inject javascript into the site to do tests. I am trying to determine which framework is being used to do form validation on the site.</p>
  
  <p>I have to change the input fields like choose "CA" for the State, or type in a last name using javascript. But I can't do that if I don't know what system they are using. Each framework has it's own rules for changing an input field and having the change register with the framework. </p>
  
  <p>I'm trying to see if there's any way to tell which framework is doing the validation, so I can use the right commands. </p>
  
  <p>In the case of toysrus.com prototype.js and jquery were both running as detected by whether the variable jQuery or Prototype existed,
  but I had to use prototype syntax to get and change a value in a form and not jquery. I had to do this through much trial and error manually.</p>
  
  <p>Is there any javascript I can write and inject into the page to tell which framework's is being used to validate a form on these sites.</p>
  
  <p>I noticed that in the case above $("#elementid") returned null, but $("elementid") returned an actual element. That told me that Prototype was doing the actual validation. Are there any tests or perhaps a js library that can determine what framework is being used on an element?</p>