How do I script a GlideDate and GlideDateTime

[asher14]

I am parsing a JSON. When a change request is submitted I want to auto populate the planned start date and planned end date. The start date show be the current users local time and the end date should be 5 minutes from the start date. How do I script the start date and end date ? I know the glidedate & glidedatetime format but it is not showing up when I open the newly submitted change request. 

//gdt get date/time

vargdt=newGlideDateTime();

vargd=newGlideDate();

vardate=gd.getByFormat("MM-dd-yyyy");

gd.setValue(gdt.localTime);

varhour=gd.getByFormat("HH:mm");

[Aman Kumar S]

Configure dictionary of Planned start date and set default value as

 javascript: new GlideDateTime();

And for planned end date as:

javascript: var y = new GlideDateTime(x); y.addSeconds(300); y;

[asher14]

heres what I have so far:

//gdt get date/time

var gdt=newGlideDateTime();

var gd=newGlideDate();

var date=gd.getByFormat("MM-dd-yyyy");

gd.setValue(gdt.localTime);

var hour=gd.getByFormat("HH:mm");