U
u object, HTMLElement, 901
UI ( user interface) events, DOM2, 336 “337
ul object, UListElement, 901
undefined data type, 58 “60
conversion of, 734
defined, 29
vs. null data type, 59 “60
overview of, 58 “59
undefined values, 113, 745
unescape ( ) method, strings, 180
Unicode character set, 54 “55
unshift( ) method, arrays, 166
URL
href property, 392
Location object for accessing, 366
URL property, Document object, 388
user interface (UI) events, DOM2, 336 “337
userAgent property, Navigator object, 536, 538 “539
user-defined objects, 133 “134, 147 “148, 754
userProfile object, 901 “902
users, privacy protection, 682
UTC (Coordinated Universal Time), 174