Determine if a date is a Saturday or a Sunday using JavaScript

You can simplify @Andrew Moore 's test even further:

if(!(myDate.getDay() % 6)) alert('Weekend!');

(Love that modulo function!)

Sure it is! The Date class has a function called getDay() which returns a integer between 0 and 6 (0 being Sunday, 6 being Saturday). So, in order to see if today is during the weekend:

var today = new Date();
if(today.getDay() == 6 || today.getDay() == 0) alert('Weekend!');

In order to see if an arbitrary date is a weekend day, you can use the following:

var myDate = new Date();
myDate.setFullYear(2009);
myDate.setMonth(7);
myDate.setDate(25);

if(myDate.getDay() == 6 || myDate.getDay() == 0) alert('Weekend!');

The Date class offers the getDay() Method that retrieves the day of the week component of the date as a number from 0 to 6 (0=Sunday, 1=Monday, etc)

var date = new Date();
switch(date.getDay()){
    case 0: alert("sunday!"); break;
    case 6: alert("saturday!"); break;
    default: alert("any other week day");
}