date - Show week number with Javascript?

Question

I have the following code that is used to show the name of the current day, followed by a set phrase.

<script type="text/javascript"> 
    <!-- 
    // Array of day names
    var dayNames = new Array(
    "It's Sunday, the weekend is nearly over",
    "Yay! Another Monday",
     "Hello Tuesday, at least you're not Monday",
     "It's Wednesday. Halfway through the week already",
     "It's Thursday.",
     "It's Friday - Hurray for the weekend",
    "Saturday Night Fever");
    var now = new Date();
    document.write(dayNames[now.getDay()] + ".");
     // -->
</script>

What I would like to do is have the current week number in brackets after the phrase. I have found the following code:

Date.prototype.getWeek = function() {
    var onejan = new Date(this.getFullYear(),0,1);
    return Math.ceil((((this - onejan) / 86400000) + onejan.getDay()+1)/7);
} 

Which was taken from http://javascript.about.com/library/blweekyear.htm but I have no idea how to add it to existing javascript code.

Answer 1

Simply add it to your current code, then call (new Date()).getWeek()

<script>
    Date.prototype.getWeek = function() {
        var onejan = new Date(this.getFullYear(), 0, 1);
        return Math.ceil((((this - onejan) / 86400000) + onejan.getDay() + 1) / 7);
    }

    var weekNumber = (new Date()).getWeek();

    var dayNames = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
    var now = new Date();
    document.write(dayNames[now.getDay()] + " (" + weekNumber + ").");
</script>