<!-- check if date DD/MM/YYYY in the past -->
function isPast(theDate){
	var myDate = (theDate).split("/");
	var date = new Date(eval(myDate[2]),eval(myDate[1])-1,eval(myDate[0]));

	var currentDate=new Date()
	var timeInMs = currentDate.getTime() - date.getTime()
	
	return (timeInMs >= 0);
}

<!-- get number of week since a date DD/MM/YYYY -->
function getWeeks(theDate){
	var myDate = (theDate).split("/");
	var date = new Date(eval(myDate[2]),eval(myDate[1])-1,eval(myDate[0]));

	var currentDate=new Date()
	var timeInMs = currentDate.getTime() - date.getTime()

	var msWeek = 7 * 24 * 60 * 60 * 1000;
	return Math.floor(timeInMs / msWeek);
}

<!-- get number of month since a date DD/MM/YYYY -->
function getMonths(theDate){
	var myDate = (theDate).split("/");
	var date = new Date(eval(myDate[2]),eval(myDate[1])-1,eval(myDate[0]));

	var currentDate=new Date()
	var timeInMs = currentDate.getTime() - date.getTime()

	var msWeek = 30 * 24 * 60 * 60 * 1000;
	return Math.floor(timeInMs / msWeek);
}

<!-- get age since birthDate DD/MM/YYYY -->
function getAge(birthDate) {
	var myDate = (birthDate).split("/");
	var dateBirth = new Date(eval(myDate[2]),eval(myDate[1])-1,eval(myDate[0]));
   
	var currentDate=new Date()
	var age=""; 
	var ageYear=0;
	var ageMonth=0;
	var ageWeek=0;
	var ageDay=0;
	
	var msYear = 365.25 * 24 * 60 * 60 * 1000;
	var msMonth = 30 * 24 * 60 * 60 * 1000;
	var msWeek = 7 * 24 * 60 * 60 * 1000;
	var msDay = 24 * 60 * 60 * 1000;

	var timeInMs = currentDate.getTime() - dateBirth.getTime() 
		
	ageYear=Math.floor(timeInMs / msYear);	
	if(ageYear < 1){
		ageMonth=Math.floor(timeInMs / msMonth);
		if(ageMonth < 1){		
			ageWeek=Math.floor(timeInMs / msWeek);
			if(ageWeek < 1){
				ageDay=Math.floor(timeInMs / msDay);
				if(ageDay < 1){
					age="0 jour";
				}				
				else if(ageDay == 1){
					age="1 jour";
				}
				else{
					age=age+ageDay+" jours";
				}
			}				
			else if(ageWeek == 1){
				age="1 semaine";
			}
			else{
				age=age+ageWeek+" semaines";
			}
		}
		else if(ageMonth == 12){
			age="1 an";
		}
		else{
			age=age+ageMonth+" mois";
		}
	}
	else if(ageYear == 1){
		age="1 an";
	}
	else{
		age=age+ageYear+" ans";
	}	
	return age;
}