참고 사이트: w3schools.com
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Strings</h2>
<p>Strings can be written with double or single quotes.</p>
<script>
document.getElementById("demo").innerHTML = 'John Doe';
</script>
</body>
</html>
변수 : 데이터 값을 저장하는 데 사용된다.
ex. var, let, const
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Variables</h2>
<p>In this example, x is defined as a variable.
Then, x is assigned the value of 6:</p>
<p id="demo"></p>
<script>
let x;
x = 6;
document.getElementById("demo").innerHTML = x;
</script>
</body>
</html>
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Operators</h2>
<p>JavaScript uses arithmetic operators to compute values (just like algebra).</p>
<p id="demo"></p>
<p id="demo2"></p>
<script>
document.getElementById("demo").innerHTML = (5 + 6) * 10;
let x, y;
x = 5;
y = 6;
document.getElementById("demo2").innerHTML = x + y;
</script>
</body>
</html>
: 값, 변수, 연산자의 조합.
(계산을 평가라고 한다)
let x, y;
x = 5 + 6;
y = x * 10;
var x, y;
x = 5 + 6;
y = x * 10;
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Expressions</h2>
<p>Expressions compute to values.</p>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = "John" + " " + "Doe";
</script>
</body>
</html>
문자열을 값으로 둔 것으로, 가운데 " "은 뛰어쓰기를 나타낸다.
따라서 아래와 같이 실행된다.
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript is Case Sensitive</h2>
<p>Try to change lastName to lastname.</p>
<p id="demo"></p>
<script>
let lastname, lastName;
lastName = "Doe";
lastname = "Peterson";
document.getElementById("demo").innerHTML = lastname;
</script>
</body>
</html>
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Comments are NOT Executed</h2>
<p id="demo"></p>
<script>
let x;
x = 5;
//x = 6; I will not be executed
document.getElementById("demo").innerHTML = x;
</script>
</body>
</html>