JavaScript - Browser - Forms and Form Fields(textarea, Function constructor, exception(try/catch))

Eloquent JavaScript

開発環境

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

Eloquent JavaScript, 2nd Ed.: A Modern Introduction to Programming(Marijn Haverbeke 著、No Starch Press)のPart 2(Browser)、Chapter 18(Forms and Form Fields)、Exercises(A JavaScript Workbench)を取り組んでみる。

Exercises(A JavaScript Workbench)

HTML5

<pre id="output0"></pre>
<textarea id="textarea0">return 'Hello, World!'</textarea>
<br>
<button id="run0">run</button>

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

JavaScript

let pre0 = document.querySelector('#output0'),
    text0 = document.querySelector('#textarea0'),
    btn0 = document.querySelector('#run0'),
    p = (text) => pre0.textContent = text;

btn0.onclick = () => {
    try {
        let f = new Function('', text0.value);
        p(f());
    } catch (e) {
        p(e);
    }
};

return 'Hello, World!'