JavaScript - hasAttribute, getAttribute, and setAttribute Extended

All three of these functions will work on attributes more than one level into an object, such as "style.border", etc.
Normally, something like

element.hasAttribute("tagName")

is false, because 'tagName' not an attribute. This function tests if an element object has a certain variable defined.

/**
 * @param  object  elem : the DOM element to be tested
 * @param  string  attr : the attribute to test for
 * @return boolean      : true if the attribute exists, false otherwise
 */
function elemHasAttribute(elem,attr) {
   var isset;
   try {
      eval("isset=typeof elem."+attr+"!='undefined';");
   } catch (e) {
      isset=false;
   }
   return isset;
}

This function works like elemHasAttribute. However, it returns the value, rather than testing for its existence.

/**
 * @param  object  elem : the DOM element to be used
 * @param  string  attr : the attribute to get
 * @return boolean      : the value of the attribute or null on error
 */
function elemGetAttribute(elem,attr) {
   try {
      return eval("elem."+attr);
   } catch (e) {
      return null;
   }
}

Works almost like the elemGetAttrubute function, except it attempts to set the attribute to the value of the third argument. If an error occurs (if you try to set a read-only attribute, etc) the function will return false.

/**
 * @param  object  elem : the DOM element to be used
 * @param  string  attr : the attribute to set
 * @param  mixed   val  : the value to set to attr
 * @return boolean      : true on success or false on error
 */
function elemGetAttribute(elem,attr,val) {
   try {
      eval("elem."+attr+"=val;");
      return true;
   } catch (e) {
      return false;
   }
}

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