タグ: programming

Javascript for

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

// for (let i = 0; i < 10; i++) {
// for (let i = 1; i < 11; i++) {
for (let i = 1; i <= 10; i++) {
    // console.log('Hello');
  console.log(`${i}: Hello`);
}

Javascript switch

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

//console.log(50 + '20');

const color = prompt('Color?');

switch (color) {
    case 'red':
        console.log('Stop!');
        break;
    case 'yellow':
        console.log('slow down');
        break;
    case 'blue':
    case 'green':
        console.log('Go!');
        break;
    default:
        console.log('Wrong color');
        break;
}

Javascript else if

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

//console.log(50 + '20');

const score = Number(prompt('Score?'));

if (score >= 90) {
    console.log('A!');
} else if (score >= 70) {
    console.log('B');
} else {
    console.log('C!');
}

Javascript 数値か文字列か

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

//console.log(50 + '20');

const n = prompt('Any number?');
console.log(Number(n) + 10);

Javascript 文字列の操作

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

const fname = 'Taro';
const lname = 'Yamada';

//console.log('My name is ' + fname + ' ' + lname + ', call me ' + fname + '!');
console.log('My name is ${fname} ${lname}, call me $(fname)!');

Javascript 文字列

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

// console.log('It is a pen.');
// console.log('It\'s a pen.');
// console.log("It's a pen.");
console.log("It's \na \npen.");

Javascript 変数に値を再代入

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

/*
Javascriptにおける数値の表現
*/
// console.log(150 * 120 * 1.1);
// console.log(150 - 130 * 1.1);
// console.log(150 * 140 * 1.1);

//変数
let price;
//定数
const rate = 1.1;

price = 150;
console.log(price * 120 * rate);
console.log(price * 130 * rate);
console.log(price * 140 * rate);

price++;
console.log(price * 120 * rate);
console.log(price * 130 * rate);
console.log(price * 140 * rate);

Javascript 変数

index.html

'use strict';

/*
Javascriptにおける数値の表現
*/
// console.log(150 * 120 * 1.1);
// console.log(150 - 130 * 1.1);
// console.log(150 * 140 * 1.1);

//変数
let price;
//定数
const rate = 1.1;

price = 150;
console.log(price * 120 * rate);
console.log(price * 130 * rate);
console.log(price * 140 * rate);

price = 151;
console.log(price * 120 * rate);
console.log(price * 130 * rate);
console.log(price * 140 * rate);

main.js

'use strict';

/*
Javascriptにおける数値の表現
*/
// console.log(150 * 120 * 1.1);
// console.log(150 - 130 * 1.1);
// console.log(150 * 140 * 1.1);

//変数
let price;
//定数
const rate = 1.1;

price = 150;
console.log(price * 120 * rate);
console.log(price * 130 * rate);
console.log(price * 140 * rate);

price = 151;
console.log(price * 120 * rate);
console.log(price * 130 * rate);
console.log(price * 140 * rate);

Javascript 定数

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

/*
Javascriptにおける数値の表現
*/
// console.log(150 * 120 * 1.1);
// console.log(150 - 130 * 1.1);
// console.log(150 * 140 * 1.1);

//定数
const price = 150;
const rate = 1.1;

console.log(price * 120 * rate);
console.log(price * 130 * rate);
console.log(price * 140 * rate);

Javascript 数値の演算

index.html

<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
  <script src="main.js"></script>
</body>
</html>

main.js

'use strict';

/*
Javascriptにおける数値の表現
*/
console.log(10 + 3);
console.log(10 - 3);
console.log(10 * 3);
console.log(10 ** 3);
console.log(10 / 3);
console.log(10 % 3);

console.log(10 + 2 * 3);
console.log((10 + 2) * 3);