JavaScript - Getting functional Introducing Functions(code)

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 3.(Getting functional Introducing Functions)、How the while loop works の CODE MAGNETS(No. 1776)) を取り組んでみる。

CODE MAGNETS(No. 1776))

コード(Emacs)

HTML5

temp = <input id="temp0" type="number" min="1" step="1" value="50"></input>
<button id="run0">run</button><button id="clear0">clear</button>
<pre id="output0"></pre>

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

JavaScript

let input0 = document.querySelector('#temp0'),
    btn0 = document.querySelector('#run0'),
    btn1 = document.querySelector('#clear0'),
    pre0 = document.querySelector('#output0');

let whatShallIWear = (temp) => {
    if (temp < 60) {
        pre0.textContent += 'Wear a jacket\n';
    } else if (temp < 70) {
        pre0.textContent += 'Wear a sweater\n';
    } else {
        pre0.textContent += 'Wear t-shert\n';
    }
};

btn0.onclick = () => {
    let temp = parseInt(input0.value, 10);
    
    whatShallIWear(temp);
};

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

whatShallIWear(60);

temp =