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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5.3
非同期プログラミングにおけるストリームの活用
125
npmjs.org/package/through2
）がよい例です。このライブラリは
Transform
ストリームの生成を単純
化してくれます。次のように単純な関数を呼び出すだけで新しい
Transform
ストリームが作れます。
const transform = through2([options], [_transform], [_flush])
同様に、
from2
（
https://npmjs.org/package/from2
）を使っても
Readable
ストリームを次のように
簡単に生成できます。
const readable = from2([options], _read)
こうした小さなライブラリを利用することの利点は、下で使用法を見れば明らかになるはずです。
through
（
https://npmjs.org/package/through
）および
from
（
https://npmjs.org/
package/from
）は
Streams1
（「
flowing
モード」で説明した旧バージョンのストリームイ
ンタフェース）をベースに作られたライブラリです。
5.3
非同期プログラミングにおけるストリームの活用
これまで見てきたように、ストリームは入出力処理だけでなく、さまざまなデータの処理に有用です。
さらに非同期の制御フローを同期的と見えるようなフローに変えることもできます。以下で具体的に見
ていきましょう。
5.3.1
逐次実行
デフォル
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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.