title: RJS: How to get the value and innerHTML of a DOM element
body: <p>I want to assign the value and the innerHTML source of a DOM element to the local ruby variables. 
  However, in my method seemly i can not make use of the RJS to complete this function.
  I don't know which method can implement it, in one words is: to assign a js variable value to a ruby local variable, how to do it ?</p>
  
  <p>The limited situations are :
         page.assign only can assign a ruby variable value to a js variable.
         page[] only can get one DOM element object, can not return it's value or innerHTML</p>