Table 5-2. Truth table for AND (
&&
)
x
y
x && y
false false false
false true
false
true
false false
true
true
true
Table 5-3. Truth table for OR (
||
)
x
y
x || y
false false false
false true
true
true
false true
true
true
true
Table 5-4. Truth table for NOT (
!
)
x
!x
false true
true
false
Looking over these tables, you’ll see that AND is
true
only if both of its operands are
true
, and OR is
false
only if both of its operands are
false
. NOT is straightforward:
it takes its only operand and inverts it.
The OR operator is sometimes called “inclusive OR” because if both operands are
true
, the result is
true
. There is also an “exclusive OR” (or XOR), which is
false
if
both operands are
true
. JavaScript doesn’t have a logical operator for XOR, but it
does have a bitwise XOR, which will be discussed later.
If you need the exclusive OR (XOR) of two variables x and y, you
can use the equivalent expression (x || y) && x !== y.
90 | Chapter 5: Expressions and Operators
