입력한 수의 합계 구하기

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>for_input_sum.html</title>
</head>
<body>
	<div>
		<input type="number" id="num" value="0">
		<input type="button" value="합계" onclick="sum();"><br>
		<hr>
		<span id="result">결과</span>
	</div>
	
	<script>
		function sum(){
			console.log("버튼클릭됨");
			
			var inputNum = document.getElementById("num");
			 	console.log(inputNum);
			
		 	var num = inputNum.value; 
			 	console.log(num);
			var pNum = parseInt(num);
				console.log(pNum);
			
			var sum = 0;
			
			for (var v = 1; v <= pNum; v++) {
				  sum += v;
			} console.log(sum);
				
			var elemNum = document.getElementById("num").value;
			
			var elemResult = document.getElementById("result");
			console.log(elemResult);
			
			 elemResult.innerHTML = sum;
			
			
			
		}
	</script>

</body>
</html>