JavaScript - Starting with the basics - Fruitful subroutines(greatest common divisor(GCD)) - Think JavaScript(?)

Think Perl 6

開発環境

• macOS Sierra - Apple (OS)
• Emacs (Text Editor)
• JavaScript (プログラミング言語)
• Node.js, Safari(JavaScript エンジン)
• Learning JavaScript [邦訳](参考書籍)

Think Perl 6: How to Think Like a Computer Scientist (Laurent Rosenfeld(著)、Allen B. Downey(著)、Oreilly & Associates Inc)のPart 1(Starting with the basics)、Chapter 5(Fruitful subroutines)の Boolean functions の Exercise 5-5.を JavaScript で取り組 んでみる。

Exercise 5-5.

コード(Emacs)

HTML5

<p>gcd(
  <input id="a0" type="number" min="1" step="1" value="12345">,
  <input id="b0" type="number" min="1" step="1" value="67890">
  ) = <span id="output0"></span>
</p>
<script src="sample5.js"></script>

JavaScript

let input_a = document.querySelector('#a0'),
    input_b = document.querySelector('#b0'),
    inputs = [input_a, input_b],
    span0 = document.querySelector('#output0');

let gcd = (a, b) => {
    return b === 0 ? a : gcd(b, a % b);
}

let output = () => {
    let a = parseInt(input_a.value, 10),
        b = parseInt(input_b.value, 10);

    span0.textContent = gcd(a, b);
};
    
inputs.forEach((input) => {    
    input.onchange = output;
});

output();

gcd( , ) =