[D-day] 날짜, 시간 카운트 > 학습

<script> 
function counter(){
	var dday = new Date("Jan 1,2021,00:00:00").getTime(); //D-day
	setInterval(function(){ 
		var now = new Date(); //Today
		var distance = dday - now; 
		var d = Math.floor(distance / (1000 * 60 * 60 * 24)); var h = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60)); 
		var m = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60)); var s = Math.floor((distance % (1000 * 60)) / 1000); 
		var show = ''; 

		if(s < 10){ s = '0'+s; } 

		if(distance<0) { 
			$('#d_day').html('D-day 마감');
		}else{ 
			if(d>0) { show = 'D-'+show+d+' : '; } //일
			
			if(h>0) { show = show+h+' : '; } //시
			
			if(m>0) { show = show+m+' : '; } //분
			
			$('#d_day').html(show+s); //초
		} 
	}, 1000); 
} 
counter(); 
</script>

<div id="d_day"></div>