HTML and CSS Reference
In-Depth Information
The value returned from the calculation daysToGo/(1000*60*60*24) will probably
contain a decimal value. The Midwest Bridal Expo Web page, however, should display
the number of days to the Midwest Bridal Expo as an integer value. The ceil() method
of the Math object is used to round up to the nearest integer (for example, if the result is
12.843 days, 13 will display because of the ceil() method). The general form of the ceil()
method is shown in Table 9-16.
Table 9-16 Math ceil() Method
General form:
var variable=ceil(value)
Comment:
where
value
may be the result of any calculation. The
ceil()
method returns a value that rounds
the value up to the next highest integer.
Examples:
var myResult=ceil(−3.8)
var myNumber=ceil(4.179)
Result:
myResult is −3
myNumber is 5
The JavaScript code for the Midwest Bridal Expo Web page is written as follows:
var daysToBridalExpo = Math.ceil(daysToGo/(1000*60*60*24))
which first finds the product of 1000*60*60*24, then divides the value stored in the
daysToGo variable by this product, and then raises the result (rounds up) to the next
highest integer.
To Calculate the Number of Days to a Future Date
The code to calculate the number of days to a future date is shown in Table 9-17. Line 19 creates the
bridalExpo object from the future date of the Midwest Bridal Expo in 2014. Line 20 subtracts the number of
milliseconds of the current date (today.getTime()) from the future date (bridalExpo.getTime()). Line 21 converts
the number of milliseconds to days.
Table 9-17 Code to Calculate the Number of Days to the Midwest Bridal Expo
Line
Code
19
var bridalExpo = new Date(“February 12, 2014”)
20
var daysToGo = bridalExpo.getTime()-today.getTime()
21
var daysToBridalExpo = Math.ceil(daysToGo/(1000*60*60*24))
The step on the next page enters the code to calculate the number of days to the Midwest Bridal Expo.
