Sams Teach Yourself JavaScript in 24 Hours

Adding JavaScript Statements

Your script now needs to determine the local and UTC times, and then display them to the browser. Fortunately, all of the hard parts, such as converting between date formats, are built in to the JavaScript interpreter.

Storing Data in Variables

To begin the script, you will use a variable to store the current date. You will learn more about variables in Hour 5, "Using Variables, Strings, and Arrays." A variable is a container that can hold a valuea number, some text, or in this case, a date.

To start writing the script, add the following line after the first <script> tag. Be sure to use the same combination of capital and lowercase letters in your version because JavaScript commands and variable names are case sensitive.

now = new Date();

This statement creates a variable called now and stores the current date and time in it. This statement and the others you will use in this script use JavaScript's built-in Date object, which enables you to conveniently handle dates and times. You'll learn more about working with dates in Hour 8, "Using Built-in Functions and Libraries."

Calculating the Results

Internally, JavaScript stores dates as the number of milliseconds since January 1, 1970. Fortunately, JavaScript includes a number of functions to convert dates and times in various ways, so you don't have to figure out how to convert milliseconds to day, date, and time.

To continue your script, add the following two statements before the final </script> tag:

localtime = now.toString();
utctime = now.toGMTString();

These statements create two new variables: localtime, containing the current time and date in a nice readable format, and utctime, containing the UTC equivalent.