May 2019
Intermediate to advanced
464 pages
9h 22m
Japanese
Content preview from Node.jsデザインパターン 第2版
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3.2
非同期パターン（素の
JavaScript
編）
51
Google
のソフトウェアエンジニアで
V8
の開発者である
Vyacheslav Egorov
が、
V8
に
おけるクロージャの内部実装に関してすばらしいブログ記事を公開しています
−
http://
mrale.ph/blog/2012/09/23/grokking-v8-closures-for-fun.html
先ほどの
spider()
は、まさにコールバック地獄の状態にあり、これまで述べてきた問題をすべて内
包しています。これからひとつずつ解決していきましょう。
3.2
非同期パターン（素の
JavaScript
編）
実際に非同期のコードを書く際には、コールバック地獄を避ける以外にも、非同期処理の制御フロー
に関するパターンを知る必要があります。たとえば、あるリストの各要素に対して非同期処理を行う場
合、単純に配列の
forEach()
メソッドを呼び出すのではなく、再帰呼び出しに似たアプローチが必要
になります。
こ
の節では、コールバック地獄を避ける方法だけでなく、ライブラリを利用しない素
す
の
JavaScript
で
一般的な制御フローを実現するためのパターンも紹介します。
3.2.1
基本原則
非同期のコードを書くときに、まず気をつけるべきことは、「クロージャを乱用しない」です。クロー
ジャは便利ですが、モジュラリティや再利用性の観点からは使用を控えるべきです。コールバック地
獄回避の第一歩は、ライブラリや特別な技術に頼るのではなく、次にあげる基本原則に従 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.