&& Operator

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Description

Used to perform a logical conjunction on two expressions.

Syntax

result = expression1 && expression2

The && operator syntax has these parts:

Part	Description
result	Any boolean variable.
expression1	Any expression.
expression2	Any expression.

Remarks

If, and only if, both expressions evaluate to True, result is True. If either expression evaluates to False, result is False.

As for all logical operators, JScript will generate runtime errors for every case in the table below where an E is indicated:

	obj	as	ns	num	bool	undef	null
obj	N	E	N	N	N	E	E
as	E	E	E	E	E	E	E
ns	N	E	N	N	N	E	E
num	N	E	N	N	N	E	E
bool	N	E	N	N	N	E	E
undef	E	E	E	E	E	E	E
null	E	E	E	E	E	E	E

obj = Object, as = Alphanumeric String, ns = Numeric String, num = Number, bool = Boolean, undef = Undefined, null = Null value.

The following are the rules for converting non-boolean values to boolean:

• All objects are true.
• Strings are false if and only if they are empty.
• null and undefined are false.
• Numbers are false if and only if they are 0.