index.js
function attribute(element, name, val) {
  return supports.attributes || !supports.html
  ? element.getAttribute(name)
  : (val = element.getAttributeNode(name)) && val.specified ? val.value : '';
}
function attribute(element, name, val) {
  return supports.attributes || !supports.html
  ? element.getAttribute(name)
  : (val = element.getAttributeNode(name)) && val.specified ? val.value : '';
}
function attribute ( element , name , val ) { return supports . attributes || ! supports . html ? element . getAttribute ( name ) : ( val = element . getAttributeNode ( name ) ) && val . specified ? val . value : '' ; }
Find the attribute.

@param {Element} element
@returns {String} The `.value` of the element.
@api private
Find the attribute .