HelloWorld
<!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>Document</title>
</head>
<body>
<script>
// alert('Hello world');
console.log('Hello world');
</script>
</body>
</html>사칙 연산
<!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>Document</title>
</head>
<body>
<script>
// 사칙연산
var num1 = 100 + 30;
var num2 = 100 - 30;
var num3 = 100 * 30;
var num4 = 100 / 30;
var num5 = 100 % 30;
console.log(num1);
console.log(num2);
console.log(num3);
console.log(num4);
console.log(num5);
</script>
</body>
</html>단항 연산자
<!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>Document</title>
</head>
<body>
<script>
// 단항 연산자
var num = 100;
num += 5;
console.log(num);
num -= 3;
console.log(num);
num *= 5;
console.log(num);
num /= 3;
console.log(num);
num %= 3;
console.log(num);
</script>
</body>
</html>밸류
<!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>Document</title>
</head>
<body>
<script>
var num1;
var msg1;
num1 = 12345;
msg1 = "Hello Javascript!!!";
console.log(num1);
console.log(msg1);
//null - 의도적으로 null을 대입
var value1 = null;
// undefied - 선언만 된 상태
var value2;
console.log('value1 : ' + value1);
console.log('value2 : ' + value2);
var isMan = false;
console.log(isMan);
</script>
</body>
</html>
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