function GetQueryVariable(variableName) {
  var query = location.search;
  variableName = variableName + '=';
  var valueStartPosition = query.indexOf(variableName) + variableName.length;
  var valueEndPosition = query.indexOf('&', valueStartPosition) > 0 ? query.indexOf('&', valueStartPosition) : query.length;
  var value = query.substring(valueStartPosition, valueEndPosition);
  return value;
}