JavaScript - A trip to Objectville - Understanding Objects(properties(states), methods(behavior))

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 5.(A trip to Objectville - Understanding Objects)、の EXERCISE(No. 3434)を取り組んでみる。

EXERCISE(No. 3434)

コード(Emacs)

HTML5

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

<script src="sample8.js"></script>

JavaScript

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


let Car = (make, model, year, color, passengers, convertible, mileage) => {
    let that = {},
        started = false,
        fuel = 0,
        start = () => {
            if (fuel > 0) {
                started = true;
            } else {
                p('the car is on empty, fill up before starting!');
            }
        },
        stop = () => started = false,
        drive = () => {
            if (started) {
                if (fuel > 0) {
                    p(`${make} ${model} goes zoom zoom!`);
                } else {
                    p('Uh oh, out of fuel.');
                    stop();
                }
            } else {
                p('You need to start the engine first.');
            }
        },
        addFuel = (amount) => {
            fuel += amount;
        };

    that.start = start;
    that.stop = stop;
    that.drive = drive;
    that.addFuel = addFuel;

    return that;
};

let output = () => {
    let fiat = Car('Fiat', '500');

    fiat.start();
    fiat.drive();
    fiat.addFuel(2);
    fiat.start();
    fiat.drive();
    fiat.drive();
    fiat.drive();
    fiat.stop();
};
btn0.onclick = output;
btn1.onclick = () => pre0.textContent = '';

output();