date.setHours() not working

Question

I am trying to subtract hours from a given date time string using javascript. My code is like:

     var cbTime = new Date();    
     cbTime = selectedTime.setHours(-5.5);

Where selectedTime is the given time (time that i pass as parameter).

So suppose selectedTime is Tue Sep 16 19:15:16 UTC+0530 2014 Ans I get is : 1410875116995

I want answer in datetime format. Am I doing something wrong here? Or there is some other solution?

Answer 1

The reason is that setHours(), setMinutes(), etc, take an Integer as a parameter. From the docs:

...

The setMinutes() method sets the minutes for a specified date according to local time.

...

Parameters:

An integer between 0 and 59, representing the minutes.

So, you could do this:

var selectedTime = new Date(),
    cbTime = new Date(); 
   
cbTime.setHours(selectedTime.getHours() - 5);
cbTime.setMinutes(selectedTime.getMinutes() - 30);

document.write('cbTime: ' + cbTime);
document.write('<br>');
document.write('selectedTime: ' + selectedTime);