February 2013
Intermediate to advanced
380 pages
7h 45m
Japanese
Content preview from Nodeクックブック
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95
レシピ 4.1 CSV ファイルを出力する
data.csv
を同じディレクトリに配置してこのスクリプトを実行すると、配列に変換されたデー
タがコンソールに出力されます。
オプションを格納したオブジェクトを
createCsvFileReader
に渡すことによって、カンマ以外
のデリミタでデータを区切ったファイルを解析することもできます。
reader
変数の宣言を以下の
ように変更すると、レシピ
4.1.1
で生成したデータ（
custom_data.csv
）を
JavaScript
配列に戻す
ことができます。
read_from_csv.js
var reader = csv.createCsvFileReader('custom_data.csv', {
'separator': ':',
'quote': '|',
'escape': '\\'
});
ミニレシピ
4.1.3
CSV
をストリームとして処理する
データを一度にすべてメモリに読み込んでから解析を実行するよりも、ストリームを使って読み
込んだ部分を逐次解析することで、実行時に使用するメモリ領域を小さくすることができます。
ya-csv
はストリームを使ってデータファイルを扱うため、以下のような実装ができます（新しい
ファイル
server.js
に記述します）。
server.js
var csv = require('ya-csv');
var http = require('http');
http.createServer(function(req, res){ ...
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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.