HTML and CSS Reference
In-Depth Information
To create the today variable:
1. Return to the clock.htm file in your text editor.
2. Insert the following lines at the beginning of the NYClock() function, as shown in
Figure 11-7:
// the today variable contains the current date and time
var today = new Date(“February 24, 2015 14:35:05”);
Figure 11-7
declaring the today variable
the today variable
stores a date object
3. Save your changes to the file.
Retrieving the Date, Month, and Year Values
A Date object stores a date and time as a numeric value that is equal to the number of
milliseconds between the specified date and time and January 1, 1970 at midnight. For
example, a Date object based on the date and time of February 24, 2015 at 2:35:05
p.m. has a hidden value equal to 1,424,810,105,000 milliseconds. Fortunately, you don't
have to work directly with this value! Instead, JavaScript provides methods you can use
to extract information from a Date object or to change a Date object's value.
To extract the day of the month from a given Date object, JavaScript provides the
getDate() method
date .getDate()
where date is a Date object or a variable that contains a Date object. For example, the
following code extracts the day value from the thisDate variable and stores the result in
the thisDay variable:
thisDate = new Date(“February 24, 2015 14:35:05”);
thisDay = thisDate.getDate();
After running these commands, the value of the thisDay variable is 24 because that is the
24 th day of the month in the specified date.
In the same fashion, the getMonth() method extracts the month value with a value
of 0 representing January, 1 representing February, and so forth up to 11 represent-
ing December. Because the getMonth() method starts counting the months with 0 for
January, you may want to add 1 to the month number to translate the value to the com-
mon system of numbering months from 1 to 12. The following JavaScript code extracts
the current month number, increases it by 1, and stores it in the thisMonth variable:
thisDate = new Date(“February 24, 2015 14:35:05”);
thisMonth = thisDate.getMonth() + 1;
The resulting value for the thisMonth variable is 2, representing the second month of
the year.
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