JavaScript - Advanced Iteration: Looping Like Crazy(Date, toLocalString(am/pm), substring, split, map, slice, filter, forEach) - Head First JavaScript(?)

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 13.(Advanced Iteration: Looping Like Crazy) の SHARPEN YOUR PENCIL(No. 8974) を JavaScript で取り組んでみる。

SHARPEN YOUR PENCIL(No. 8974)

コード(Emacs)

HTML5

<input id="file0" type="file">
<br>
<button id="run0">run</button>
<button id="clear0">clear</button>
<pre id="output0"></pre>

<script src="sample1.js"></script>

JavaScript

let input0 = document.querySelector('#file0'),
    btn0 = document.querySelector('#run0'),
    btn1 = document.querySelector('#clear0'),
    pre0 = document.querySelector('#output0'),
    p = (x) => pre0.textContent += x + '\n';

let po = (o) => {
    Object.keys(o).forEach((k) => {
        p(`${k}: ${o[k]}`);
    });
};

let convert2ampm = (s) => {
    let d = s.split(':'),
        h = parseInt(d[0], 10),
        m = parseInt(d[1], 10);

    let date = new Date(0, 0, 0, h, m),
        ts = date.toLocaleString();
    
    ts = ts.split(', ')[1];
    
    return ts.substring(ts, ts.length - 6) + ts.substring(ts.length - 2);
};
let output = () => {
    let reader = new FileReader();
    reader.onload = () => {
        let data = reader.result
            .split('\n')
            .slice(1)
            .map((x) => x.trim())
            .filter((x) => x !== ''),
            flight = {};

        data
            .map((x) => x.split(','))
            .forEach((x) => {
                flight[x[0]] = x[1];
            });
        po(flight);
        p('');
        
        let flight2 = {};
        
        Object.keys(flight)
            .map((k) => flight2[convert2ampm(k)] =
                 flight[k]
                 .split(' ')
                 .map((s) => s[0].toUpperCase() + s.substring(1).toLowerCase())
                 .join(' '));
        po(flight2);
    };
    reader.readAsText(input0.files[0]);
};

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

output();