node 读取多个文件、合并多个文件、读写多个文件

一、读取文件

1、找去匹配的内容
let fs = require('fs')
let content = fs.readFileSync('/Users/**/desktop/Test.txt', 'utf-8')
console.log(content.match(/uD83C[uDF00-uDFFF]|uD83D[uDC00-uDE4F]/g))

2、读取文件

var fs = require('fs');
let content = fs.readFileSync('/Users/**/desktop/mark.log', 'utf-8')
fs.appendFile('/Users/caofan/desktop/Test.txt', content, function (err) {
    if (err) throw err;
    console.log('The "data to append" was appended to file!');
});

3.按行读取单个文件

var readline = require('readline');
var fs = require('fs');
var os = require('os');

var fReadName = '/Users/**/desktop/title/title_20171101.log';
var fWriteName = './emoji1.csv';
var fRead = fs.createReadStream(fReadName);
var fWrite = fs.createWriteStream(fWriteName);
var enableWriteIndex = true;

var objReadline = readline.createInterface({
    input: fRead
});

var index = 1;
var matchArr = [];

objReadline.on('line', (line)=>{
    if (enableWriteIndex) {
        if(line.match(/uD83C[uDF00-uDFFF]|uD83D[uDC00-uDE4F]/g)){
            matchArr.push(index)
            var tmp = line;
            fWrite.write(tmp + os.EOL);
            // if (matchArr.length <= 10) {      //输出匹配的前10条
            //     console.log(line)
            //     // fs.writeFileSync(fWriteName, line+ '
', 'utf8');
            //     var tmp = 'line' + matchArr.length + ':' + line;
            //     fWrite.write(tmp + os.EOL);   //  将匹配的前10条写入另一个文件 
            // }
        }
        index ++;
    }
});

fRead.on('end', ()=>{
    enableWriteIndex = false;
    console.log(matchArr.length)  // 总共匹配的条数
});

objReadline.on('close', ()=>{
});

4. 合并目录下的多个文件到另一个文件

var fs = require("fs");
var path = require('path');
//配置远程路径
var remotePath = "./emoji";  // 相对路径
//读取文件目录
fs.readdir(remotePath,function(err,files){
    if(err){
        console.log(err);
        return;
    }
    files.forEach(function(filename){
        var filedir = path.join(remotePath,filename);
        fs.stat(filedir,function(err, stats){
            if (err) throw err;
            if(stats.isFile()){
                if(/emoji/.test(filename)) {
                     console.log(filename)
                     let content = fs.readFileSync(path.join(remotePath,filename), 'utf-8')
                     fs.appendFile('/Users/caofan/desktop/Test.txt', content)
                }
            } else if(stats.isDirectory()){
                return false
            }
        });
    });
});

5. 读取文件目录下的所有文件，匹配内容输出到新的文件

var fs = require('fs');
var readline = require('readline');
var path = require('path');
var os = require('os');

//解析需要遍历的文件夹
var filePath = path.resolve('/Users/**/desktop/title');
//调用文件遍历方法
fileDisplay(filePath);
var fWriteName = './emojis2.csv';
var matchArr = [];
var index = 1;
function fileDisplay(filePath){
    //根据文件路径读取文件，返回文件列表
    fs.readdir(filePath,function(err,files){
        if(err){
            console.warn(err)
        }else{
            //遍历读取到的文件列表
            files.forEach(function(filename){
                //获取当前文件的绝对路径
                var filedir = path.join(filePath,filename);
                //根据文件路径获取文件信息，返回一个fs.Stats对象
                fs.stat(filedir,function(eror,stats){
                    if(eror){
                        console.warn('获取文件stats失败');
                    }else{
                        var isFile = stats.isFile();//是文件
                        var isDir = stats.isDirectory();//是文件夹
                        if(isFile){
                            if(/title_201711/.test(filename)) {
                                var fRead = fs.createReadStream(filedir);
                                var fWrite = fs.createWriteStream(fWriteName);
                                var enableWriteIndex = true;
                                var objReadline = readline.createInterface({      // 按行读取
                                    input: fRead
                                });
                                objReadline.on('line', (line)=>{
                                    if (enableWriteIndex) {
                                        if(/[]{}<>[@【】「」#*^]/.test(line)){
                                            matchArr.push(index)
                                            if (matchArr.length <= 10000) {
                                                var tmp = line;
                                                console.log(line)
                                                fWrite.write(tmp + os.EOL);
                                            }
                                        }
                                        index ++;
                                    }
                                });
                                objReadline.on('close', ()=>{
                                    console.log(matchArr.length)
                                   // console.log(index)
                                });
                            }
                        }
                        if(isDir){
                            fileDisplay(filedir);//递归，如果是文件夹，就继续遍历该文件夹下面的文件
                        }
                    }
                })
            });
        }
    });
当然，这些功能都能通过shell命令行实现。只是有时utf8编码问题导致正则在命令行匹配不到准确数据，所以在 node 中实现。