new class (생성자) , 오버로딩 개념
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>객체</title>
</head>
<body>
<script>
//number() 객체
var str1 = '8293';
var str2 = 'abc';
var objnum = new Number('1234');
var num =1234;
document.write('문자열 + 숫지형:' + (str1 + num) + '</br>');
document.write('문자열 + 숫지형:' + (objnum + num) + '</br>'); // 객체 + Number = number? 그래서 objnum & Number가 둘다 객체다.
document.write('문자열 + 숫지형:' + Number(str1) + '</br>');
document.write('문자열 + 숫지형:' + Number(str2) + '</br>');
</script>
</body>
</html>