nodejs实现日志读取、日志查找及日志刷新的方法分析

function readLog(date,type，operation){
//函数接受3个参数，日期、精度(天时分秒)和操作（查找、刷新或者默认）
 if(date){
 //如果有时间参数则对时间参数进行处理（一般日志名称都是时间加类型）
 var dataStr = arguments[0];
 var date = dataStr.slice(0,10);
 var hour = dataStr.slice(11,13);
 var minute = dataStr.slice(11,16);
 var second =dataStr.slice(11,19);
 var type = arguments[1];
 //获取精度
 }else{
 //若无时间参数则获取当前时间，然后精度默认
 var date = new Date(+new Date()+8*3600*1000).toISOString().replace(/T/g,' ').replace(/\.[\d]{3}Z/,'').slice(0,10);
 var type=null;
 }
 var op = arguments[2];
 var countResult = 0;
 //对日志结果进行统计
 var logPath = appDirName.slice(0,-3)+'log\\'+'ivsvr_'+date+'.log';
 //拼接日志文件名称
 var logStr = '';
 fs.stat(logPath, function (err, stats) {
 //获取对应的日志文件状态
 if(err){
 //日志不存在或者异常处理信息
 $('#logTipInfo tr td').html('无日志信息可供查看');
 console.log(err);
 }else{
 var lineCount = 0;
 var readline = require('readline');
 var fReadName = logPath;
 var fRead = fs.createReadStream(fReadName);
 var objReadline = readline.createInterface({
 input: fRead,
 });
 //按行读取日志
 objReadline.on('line', (line)=>{
 var itemStr = $.trim(line);
 var time = itemStr.slice(0,19);
 var content = itemStr.substr(20);
 if(!time || !content){return;}
 ++ lineCount;
 //计数行数
 var matched = true;
 var itemStr = $.trim(line);
 var itemArr = itemStr.split(' ');
 var logDate = itemArr[0];
 var logTime = itemArr[1];
 var time = logDate+' '+logTime;
 switch(type){
 //进度查找过滤
 case '0':
 case null:
 matched = true;
 break;
 case '1':
 var timeSplit = logTime.slice(0,2);
 if(timeSplit == hour){
 matched = true;
 break;
 }
 matched = false;
 break;
 case '2':
 var timeSplit = logTime.slice(0,5);
 if(timeSplit == minute){
 matched = true;
 break;
 }
 matched = false;
 break;
 case '3':
 var timeSplit = logTime.slice(0,8);
 if(timeSplit == second){
 matched = true;
 break;
 }
 matched = false;
 break;
 default:
 console.log('unkonw type!');
 break;
 }
 if(matched === true &&(lineCount>logReadFlag)){
 //日志结果格式化