<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
var a = true;
var b = 100;
var c = "Hello";
var d = Math.sqrt(4); // 제곱근
var e = Math.sqrt(-4); // NaN : Not a Number : 존재하지 않는 숫자
document.write(a + "<br>");
document.write(b + "<br>");
document.write(c + "<br>");
document.write(d + "<br>");
document.write(e + "<br>");
document.write("----------------<br/>");
// 1. 숫자로 변환 : Number(값)
document.write(Number(a) + "<br>"); // true == 1, false == 0
document.write(Number(b) + "<br>");
document.write(Number(c) + "<br>"); // "Hello"는 숫자 변환이 안되므로 NaN
document.write(Number(d) + "<br>");
document.write(Number(e) + "<br>");
document.write("----------------<br/>");
// 2. 문자열로 변환 : String(값)
document.write(String(a) + "<br>");
document.write(String(b) + "<br>");
document.write(String(c) + "<br>");
document.write(String(d) + "<br>");
document.write(String(e) + "<br>");
document.write("----------------<br/>");
</script>
</head>
<body>
</body>
</html>
