JavaScript - Serious types - Types, Equality, Conversion and All That Jazz(undefined)

Head First JavaScript Programming

開発環境

• macOS Sierra - Apple (OS)
• Emacs (Text Editor)
• JavaScript (プログラミング言語)
• Safari(Web browser)

Head First JavaScript Programming (Eric T. Freeman (著)、Elisabeth Robson (著)、O'Reilly Media)の Chapter 7.(Serious types - Types, Equality, Conversion and All That Jazz)の WHO AM I?(No. 4025)を取り組んでみる。

WHO AM I?(No. 4025)

コード(Emacs)

HTML5

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

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

JavaScript

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


let output = () => {
    let v,
        o = {a:1, b:2};

    delete o.b;
    
    [
        [(() => {return})(), undefined],
        [v, undefined],
        [[][1], undefined],
        [o.c, undefined],
        [o.b, undefined]
    ].forEach((x) => {
        p(((a, b) => a === b)(...x));
    });
};

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

output();