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 10.(Function Decorators: Wrapping Functions) の SHARPEN YOUR PENCIL(No. 7593) を JavaScript で取り組んでみる。
SHARPEN YOUR PENCIL(No. 7593)
コード(Emacs)
HTML5
<button id="run0">run</button> <button id="clear0">clear</button> <pre id="output0"></pre> <script src="sample5.js"></script>
JavaScript
let btn0 = document.querySelector('#run0'), btn1 = document.querySelector('#clear0'), pre0 = document.querySelector('#output0'), session = {}; let checkLoggedIn = (fn) => { return (...args) => { if (session['logged_in']) { return fn(...args); } return 'You are NOT logged in'; }; }; let test = checkLoggedIn( (a, b) => { return `logged in(${a + b})`; } ); let output = () => { pre0.textContent += test() + '\n'; session['logged_in'] = true; pre0.textContent += test(5, 10) + '\n'; delete session['logged_in']; pre0.textContent += test() + '\n'; }; btn0.onclick = output; btn1.onclick = () => { pre0.textContent = ''; }; output();
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