nodejs fs 流的方式读写文件

var fs = require('fs')

var myReadStream = fs.createReadStream(__dirname + '/book.txt')
var myWriteStream = fs.createWriteStream(__dirname + '/copy.txt')

myReadStream.setEncoding('utf8')

var data = ''

myReadStream.on('data', function(chunk){
    data += chunk
})

myReadStream.on('end', function(){
    console.log(data)
    myWriteStream.write(data)
})