Page 159 - DCAP202_Fundamentals of Web Programming

Fundamentals of Web Programming

Notes you can let JavaScript create a Date object based on your visitor’s system clock. It is usually best
to let JavaScript simply use the system clock.

Syntax

new Date( )
new Date(milliseconds)
new Date(datestring)
new Date(year,month,date[,hour,minute,second,millisecond ])
The Date object has been created, and now we have a variable that holds the current date! To get
the information we need to print out, we have to utilize some or all of the following functions:
 getTime() - Number of milliseconds since 1/1/1970 @ 12:00 AM

 getSeconds() - Number of seconds (0-59)
 getMinutes() - Number of minutes (0-59)
 getHours() - Number of hours (0-23)
 getDay() - Day of the week(0-6). 0 = Sunday, ... , 6 = Saturday

 getDate() - Day of the month (0-31)
 getMonth() - Number of month (0-11)
 getFullYear() - The four digit year (1970-9999)

Example:
<h4>It is now
<script type=”text/javascript”>
<!—
var currentTime = new Date()
var month = currentTime.getMonth() + 1
var day = currentTime.getDate()
var year = currentTime.getFullYear()
document.write(month + “/” + day + “/” + year)
//—>
</script>
</h4>

13.1.2 Creating Arrays and Objects

JavaScript objects are collections of properties and methods. A method is a function that is a
member of an object. A property is a value or set of values (in the form of an array or object) that
is a member of an object. JavaScript supports four kinds of objects: intrinsic objects, objects you
create, host objects, which are provided by the host (such as window and document in Internet
Explorer) and ActiveX objects.
All objects in JavaScript support “expando” properties and methods, or properties that can be
added and removed at run time. These properties and methods can have any name, including
numbers. If the name of the property or method is a simple identifier, it can be written after the
object name with a period, such as:
var myObj = new Object();
myObj.name = “Fred”;
myObj.age = 42;

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