Trick: Getting the Name of Enclosing Form (JS)

Here is a small Javascript function which returns the name of the enclosing form for an element. I found it quite useful in refactoring and supporting an old web application – some old JS code required a form name to access some input fields, so I created this JS snippet to be able to use the old code in a more generic way.

function getEnclosingFormName(field_name){
 var obj = document.getElementById(field_name);
 var node = obj.parentNode;
    var i=0;
          while (node.tagName !='FORM' && node !=null && node.tagName!='HTML'){
           node = node.parentNode;
          }
         if (node.tagName == 'HTML') {
          return '';
         } 
        return node.name;
 }