Jump a week from another date

function bounce() {
	d = document.periodsel;
 
	var bog = new Array();
	bog = d.date1a.value.split("-");
	ra = bog[0];
	re = bog[1]-1;
	ro = bog[2];
 
	dod = new Date(ra,re,ro);
	domo = dod.getMonth()+1;
	doda = dod.getDate()+6;
 
	if(doda <= '9')
		doda = '0'+doda;
 
	ere = dod.getFullYear()+'-'+domo+'-'+doda;
 
	d.date1b.value = ere;
	return true;
}