function determineAge(birthdate){
	var dateInput = new Date(birthdate);
	var today = new Date();
	var dateInputYear = dateInput.getYear();
	var todayYear = today.getYear();
	var dateDiff = todayYear - dateInputYear;

	if(dateInput.getMonth() < today.getMonth() &&  dateInput.getDate() < today.getDate()){
		--dateDiff;
	}

	return dateDiff
}

function btnParseDate_onclick(){
	// assign textbox elements to variables for easier access
	var dateOfBirthTextbox = document.getElementById("txtDOB");
	var outputTextbox = document.getElementById("txtOutput");

	var dateInput = new Date(dateOfBirthTextbox.value);
	var today = new Date();

	outputTextbox.value = "Today's date: " today.toDateString() + "/n" + "Your Birth Date: " dateInput.toDateString() + "/n" "Age: " + determineAge(dateOfBirthTextbox.value)
}