HTML and CSS Reference
In-Depth Information
EXPLANATION
(
CONTINUED
)
2
When the bitwise
|
(OR) operator is applied to
1111 | 1001
, the result is binary
1111 or decimal 15.
3
When the bitwise
^
(Exclusive OR) is applied to
1111 ^ 1001
, the result is binary
0110 or decimal 6.
4
9<<2
yields 36, because 1001 shifted two bits to the left becomes 100100, which
is decimal 36.
5
9>>2
yields 2, because 1001 shifted two bits to the right becomes 10, which is dec-
imal 2.
6
-9 >> 2
yields
-3
, because the sign is preserved.
7
15 >>> 2
yields 3, because 1111 shifted two bits to the right becomes 0011, which
is decimal 3. For nonnegative numbers, zero-fill right shift and sign-propagating
right shift yield the same result. (See Figure 5.19.)
Figure 5.19
Output from Example 5.13.
Data Type Conversion
As defined earlier, JavaScript is a loosely typed language, which really means that you don't
have to be concerned about what kind of data is stored in a variable. You can assign a num-
ber to
x
on one line and on the next line assign a string to
x
, you can compare numbers
and strings, strings and Booleans, and so on. JavaScript automatically converts values
when it assigns values to a variable or evaluates an expression. If data types are mixed (i.e.,
a number is compared with a string, a Boolean is compared with a number, a string is com-
pared with a Boolean), JavaScript must decide how to handle the expression. Most of the
time, letting JavaScript handle the data works fine, but there are times when you want to
force a conversion of one type to another. For example, if you prompt a user for input, the
input is set as a string. But, suppose you want to perform calculations on the incoming
data, making it necessary to convert the strings to numbers. When using the
+
operator
you want to add two numbers that have been entered as strings, not concatenate them, so
you will then need to convert the data from string to number.
