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May 20, 2004 

JavaScript

Script Tag

<script language="JavaScript">
<!-- Hide from non-JavaScript browsers

        Script commands and comments

// Stop hiding from older browsers  -->
</script>

 

Sending Output to a Web Page

<script language="JavaScript">
<!-- Hide from non-JavaScript browsers

      document.write("Today is May 20, 2004<br>")
      document.write("Only 180 days until Christmas")

// Stop hiding from older browsers  -->
</script>

Example 1

 

 

Working with Variables and Data

Declaring Variables

var variable;
var variable = value;
variable = value;

 

<script language="JavaScript">
<!-- Hide from non-JavaScript browsers

      var Today;
      var ThisDay;
      var ThisMonth;
      var ThisYear;
      var DaysLeft;
      document.write("Today is May 20, 2004<br>")
      document.write("Only 180 days until Christmas")

// Stop hiding from older browsers  -->
</script>

 

Working with Dates

Variable = new Date("month, day, year, hours:minute:seconds

Variable = new Date(year, month, day, hours, minutes, seconds)

<script language="JavaScript">
<!-- Hide from non-JavaScript browsers

      var Today=new Date("May 20, 2004);
      var ThisDay;
      var ThisMonth;
      var ThisYear;
      var DaysLeft;
      document.write("Today is May 20, 2004<br>");
      document.write("Only 180 days until Christmas");

// Stop hiding from older browsers  -->
</script>

 

Retrieving Values

Today.getSeconds() Retrieves the seconds form the date
Today.getMinutes() Retrieves the minutes from the date
Today.getHours() Retrieves the hours from the date
Today.getDate() Retrieves the day of the month
Today.getDay Retrieves the day of the week
(0 = Sunday, 1 = Monday, etc.)
Today.getMonth() Retrieves the month
(0 = Jan, 1 = Feb., etc.)
Today.getFullYear() Retrieves the four digit year
Today.getTime() Retrieves the time expressed in milliseconds since December 31, 1969, 6 pm

 

<script language="JavaScript">
<!-- Hide from non-JavaScript browsers

      var Today=new Date("May 20, 2004");
      var ThisDay=Today.getDate();
      var ThisMonth=Today.getMonth()+1;
      var ThisYear=Today.getFullYear();
      var DaysLeft=999;
      document.write("Today is "+ThisMonth+"/"+ThisDay+"/"+ThisYear+"<br>");
      document.write("Only "+DaysLeft+" days until Christmas");

// Stop hiding from older browsers  -->
</script>

Example 2

Creating Functions

function function_name(parameters) {
  JavaScript commands
}

function ShowDate(Date) {
document.write("Today is "+date+<br>");

 

Create the XmasDays Function

 

XYear   -  The current Year
XDay  -   Christmas Day
DayCount  -  Number of days until Christmas

Note:
var DayCount=(XDay - CurrentDay)/<1000*60*60*24);

Create the Function:

<script language="JavaScript">
<!-- Hide from non-JavaScript browsers
function XmasDays(CurrentDay) {
var XYear=CurrentDay.getFullYear();
var XDay=new Date("December, 25, 2004");
XDay.setFullYear(XYear);
var DayCount=(XDay-CurrentDay)/(1000*60*60*24);
DayCount=Math.round(DayCount);
return DayCount;
}

Call the Function

<script language="JavaScript">
<!-- Hide from non-JavaScript browsers
var Today=new Date("May 20, 2004");
var ThisDay=Today.getDate();
var ThisMonth=Today.getMonth()+1;
var ThisYear=Today.getFullYear();
var DaysLeft=XmasDays(Today);
document.write("Today is "+ThisMonth+"/"+ThisDay+"/"+ThisYear+"<br>");
document.write("Only "+DaysLeft+" days until Christmas");

 

Example 3

Create a Conditional Statement

if (DaysLeft>) {
document.write("Only "+DaysLeft+" days until Christmas");
} else {
document.write("Happy Holidays from the North Pole");
}

 

Example 4

Reference  New Perspectives by Thompson

Next Month:  June 17, 2004
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