利用nodejs實現：逐行讀寫（從一個文件逐行復制到另外一個文件）；逐行讀取、處理和寫入（讀取一行，處理後，寫入另一個文件）

1.所需要的模塊： fs，os，readline

2.具體實現：

　a. 功能的實現：readWriteFileByLine.js

var fs = require(‘fs-extra‘);
var os = require(‘os‘);
var rl =  require(‘readline‘);

/**
 * 按行讀寫，無讀取內容的處理，類似單純的復制功能
 * @param {string} readName 
 * @param {string} writeName 
 
 
*/
var readWriteFileByLine = function(readName, writeName){
    var readStream =  fs.createReadStream(readName);
    var writeStream = fs.createWriteStream(writeName);
    var readLine = rl.createInterface({
        input: readStream,
        output: writeStream,
        terminal: true
    })
}

/**
 * 按行讀寫，中間包涵對讀取的行內容的處理
 * @param {string} readName 
 * @param {string} writeName 
 * @param {Function} callback 
 
 
*/
var readWriteFileByLineWithProcess = function(readName,writeName,callback){
    var readStream = fs.createReadStream(readName);
    var writeStream = fs.createWriteStream(writeName);
    var readLine = rl.createInterface({
        input: readStream
    })
    readLine.on(‘line‘,function(line){
        
 
var rs = callback(line);
        writeStream.write(rs + os.EOL);
    })
}

exports.readWriteFileByLine = readWriteFileByLine;
exports.readWriteFileByLineWithProcess = readWriteFileByLineWithProcess

　　b. 功能的調用：index.js

var rwByLine = require(‘./lib/readWriteFileByLine.js‘)

//按行讀寫，對行做字符替換處理
var readName = ‘./obj.txt‘;
var writeName = ‘./rt.txt‘;
rwByLine.readWriteFileByLineWithProcess(readName,writeName,function(line){
    var rs = line.toString().replace("\\",‘\/‘);
    return rs;
})

//按行讀寫，無處理
readName = ‘./obj.txt‘;
writeName = ‘./rt1.txt‘;
rwByLine.readWriteFileByLine(readName,writeName);

nodejs 文本逐行讀寫功能的實現