JavaScript - Array Data: Working with Ordered Data(square bracket notation, slice method, index, join method)

Head First Python

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)

Head First Python (Paul Barry (著)、O'Reilly Media)のChapter 2.(List Data: Working with Ordered Data)、Reviewing Our Experiments の SHARPEN YOUR PENCIL(No. 1802) を JavaScript で取り組んでみる。

SHARPEN YOUR PENCIL(No. 1802)

コード(Emacs)

HTML5

<pre id="output0"></pre>

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

<script src="sample2.js"></script>

JavaScript

let pre0 = document.querySelector('#output0'),
    btn0 = document.querySelector('#run0'),
    btn1 = document.querySelector('#clear0'),
    range = (start, end, step=1) => {
        let res = [];

        for (let i = start; i < end; i += step) {
            res.push(i);
        }
        return res;
    },
    p = (x) => pre0.textContent += x + '\n';

let output = () => {
    let phrase = "Don't panic!",
        plist = phrase.split('');

    p(phrase);
    p(plist);

    let newPhrase = plist.slice(1, 3).join('');
    newPhrase += `${plist[5]}${plist[4]}${plist[7]}${plist[6]}`;
    
    p(plist);
    p(newPhrase);
};

let clear = () => pre0.textContent = '';

btn0.onclick = output;
btn1.onclick = clear;

output();