date / time object in javascript, Qustion about day of the week

[Amzul]

hello all

i am breaking my head over this and there isnt any good solution that i have saw til now, my problam is that i want to tell the date of a sertin day what was choosen

[HTML]<select id="7_day" name ="7days">
<option value="0">Sunda y</option>
<option value="1">Monda y</option>
<option value="2">Tuesd ay</option>
<option value="3">Wedne sday</option>
<option value="4">Thurs day</option>
<option value="5">Frida y</option>
<option value="6">Satur day</option>
</selectt>[/HTML]
when the user choose one of this days i will be able to get the date of all the last 5 sunday's for example

the problam i am getting is when trying to minus 7 out of the:

today = new Date();
alert(today.getDate()-7 )

this is fine as long as we are not at the age.

alert (today.getDate()-28)

will bring back minus
i dont want to calculate it as intgers i want to calculate it as dates is it possible?? in php i would use mktime but js dont have it :(
somthing like that :

<?php
$date= date("Y-m-d");
$day = explode("-",$date);
$lastWeek= strftime("%Y-%m-%d",(mktime(0,0,0,$day[1],$day[2]-7,$day[0])));
?>

any idea??

[acoder]

Use the setDate() method:

var today = new Date();
var newDate = new Date();
newDate.setDate(today.getDate()-7);

[Amzul]

that return seconds since epoch, (progress :))
how can i convert it to string like this yyyy-mm-dd

[acoder]

that return seconds since epoch, (progress :))
how can i convert it to string like this yyyy-mm-dd

Just output a string using the get*** methods:

alert(newDate.getFullYear() + "-" + (newDate.getMonth()+1) + "-" + newDate.getDate());

[Amzul]

thanks,
its all make sense now

[acoder]

You're welcome. Glad it helped.