Java Reference
In-Depth Information
4.
Finally, reload the page again, but this time, enter
212
in the prompt box. The two lines shown in
Figure 3-5 will appear in the page.
figure 3-5
The first part of the script block in this page is similar to the example
ch2 _ example4.html
in
Chapter 2. You declare two variables,
degFahren
and
degCent
. The variable
degFahren
is given
an initial value obtained from the user with the
prompt()
function. Note the
prompt()
function
returns a string value, which you then convert to a numeric value using the
parseInt()
function. The
variable
degCent
is initialized to the result of the calculation
5/9 * (degFahren ‐ 32)
, which is the
Fahrenheit‐to‐centigrade conversion calculation:
var degFahren = parseInt(prompt("Enter the degrees Fahrenheit", 32), 10);
var degCent = 5/9 * (degFahren - 32);
Then you write the result of your calculation to the page:
document.write(degFahren + "\xB0 Fahrenheit is " + degCent +
"\xB0 centigrade<br />");
Now comes the new code; the first of two
if
statements:
if (degCent < 0) {
document.write("That's below the freezing point of water");
}
This
if
statement has the condition that asks, “Is the value of the variable
degCent
less than zero?” If
the answer is yes (
true
), the code inside the curly braces executes. In this case, you write a sentence to
the page using
document.write()
. If the answer is no (
false
), the processing moves on to the next line
after the closing brace. Also worth noting is the fact that the code inside the
if
statement's opening
brace is indented. This is not necessary, but it is a good practice to get into because it makes your code
much easier to read.
