function validateUSZip( strValue ) {
/************************************************
DESCRIPTION: Validates that a string a United
  States zip code in 5 digit format or zip+4
  format. 99999 or 99999-9999
    
PARAMETERS:
   strValue - String to be tested for validity
   
RETURNS:
   True if valid, otherwise false.

*************************************************/
var objRegExp  = /(^\d{5}$)|(^\d{5}-\d{4}$)/;
 
  //check for valid US Zipcode
  return objRegExp.test(strValue);
}