We can set the minutes part of the date object by using setMinutes function Sets the minutes value in the Date object using local time. Set methods take optional arguments using the value returned from corresponding get methods, if you do not specify an optional argument. For example, if the numSeconds argument not specified, JavaScript uses the value returned from the getSeconds method.

Syntax

dateObj.setMinutes(numMinutes[, numSeconds[, numMilli]]) 

dateObj
    Required. Any Date object.

numMinutes
    Required. A numeric value equal to the minutes value. Must be supplied if either of the following arguments is used.

numSeconds
    Optional. A numeric value equal to the seconds value. Must be supplied if the numMilli argument is used.

numMilli
    Optional. A numeric value equal to the milliseconds value.


<script type="text/javascript"> 
var dt= new Date();
document.write( dt + "<br><br>");
dt.setMinutes(15);
document.write( "<br><br>" + dt );
</script>

Here is the output based on your time zone and date and time of your computer

Tue Nov 17 2015 11:56:04 GMT+0530 (India Standard Time)
Tue Nov 17 2015 11:15:04 GMT+0530 (India Standard Time)