Microsoft® JScript™  Operator 
Language Reference Version 1

Used to perform a logical disjunction on two expressions.
result = expression1  expression2The  operator syntax has these parts:
Part Description result Any variable. expression1 Any expression. expression2 Any expression.
If either or both expressions evaluate to True, result is True. The following table illustrates how result is determined:
If expression1 is And expression2 is The result is True True True True False True False True True False False False For information on when a runtime error is generated by the && operator, see the Operator Behavior table.
JScript uses the following rules for converting nonBoolean values to Boolean values:
 All objects are considered true.
 Strings are considered false if and only if they are empty.
 null and undefined are considered false.
 Numbers are false if and only if they are 0.