JavaScript - Starting with the basics - Strings(String Traversal with a while or for Loop, Ducklings, codePointAt method, String.fromCodePoint method)

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 7(Strings)、String Traversal with a while or for Loop の Exercise: The Ducklings.を JavaScript で取り組んでみる。

Exercise: The Ducklings.

コード(Emacs)

HTML5

<pre id="output0"></pre>
<button id="run0">run</button>
<button id="clear0">clear</button>

<script src="sample_duckl.js"></script>

JavaScript

let btn0 = document.querySelector('#run0'),
    btn1 = document.querySelector('#clear0'),
    pre0 = document.querySelector('#output0'),
    p = (x) => pre0.textContent += x + '\n',
    range = (start, end, step=1) => {
        let result = [];
        for (let i = start; i < end; i += step) {
            result.push(i);
        }
        return result;
    };

let output = () => {
    let suffix = 'ack';
    p(
    range('J'.codePointAt(0), 'Q'.codePointAt('Q') + 1)
            .map((code) => {
                let c = String.fromCodePoint(code);

                if (c === 'O' || c === 'Q') {
                    return `${c}u${suffix}`
                }
                return `${c}${suffix}`;
            })
            .join('\n')
    );
};

btn0.onclick = output;
btn1.onclick = () => pre0.textContent = '';

output();