node.js 管道到标准输出和可写流
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/17822437/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Pipe to stdout and writeable stream
提问by Nick Tomlin
I'm piping a file through a duplex string (courtesy of through) and I'm having trouble printing information to stdoutandwriting to the file. One or the other works just fine.
我正在通过双工字符串（由through 提供）传输文件，但在向文件打印信息stdout和向文件写入信息时遇到问题。一个或另一个工作得很好。
var fs = require('fs');
var path = require('path');
var through = require('through'); // easy duplexing, i'm young
catify = new through(function(data){
this.queue(data.toString().replace(/(woof)/gi, 'meow'));
});
var reader = fs.createReadStream('dogDiary.txt'); // woof woof etc.
var writer = fs.createWriteStream(path.normalize('generated/catDiary.txt')); // meow meow etc.
// yay!
reader.pipe(catify).pipe(writer)
// blank file. T_T
reader.pipe(catify).pipe(process.stdout).pipe(writer)
I'm assuming this is because process.stdoutis a writeable stream, but I'm not sure how to do what I want (i've tried passing {end: false}to no avail).
我假设这是因为process.stdout是一个可写的流，但我不确定如何做我想做的事情（我试过传递{end: false}无济于事）。
Still struggling to wrap my head around streams, so forgive me if i've missed something obvious : )
仍在努力将我的头环绕在溪流中，所以如果我错过了一些明显的东西，请原谅我:)
回答by Jonathan Ong
I think what you want is:
我想你想要的是：
reader.pipe(catify)
catify.pipe(writer)
catify.pipe(process.stdout)
These needed to be separated because pipes return their destinations and not their source.
这些需要分开，因为管道返回它们的目的地而不是它们的源。
