Check for attribute support with JS

gistfile1.js

function checkAttribute(element, attribute) {
 var test = document.createElement(element);
 if (attribute in test) {
   return true;
  } else {
   return false;
  }
}

checkAttribute("input", "required");

//or a tidier version

function checkAttribute(elem, attr) {
  return attr in document.createElement(elem);
}