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)){
        //日志结果格式化输出呈现
          countResult ++;
          var result = itemArr[2];
          if(result == 'err'){
            var operation = itemArr[4];
            result = '失败：'+itemArr[5]+' '+(itemArr[6]?itemArr[6]:'');
          }else{
            var operation = itemArr[4]+' '+itemArr[5]+(itemArr[6]?itemArr[6]:'');
            result = '成功';
          }
          logStr += ''+time+''+operation+''+result+''
        }
        logStr += ''+time+''+content+''
      });
      objReadline.on('close', ()=>{
        if(logReadFlag == 0 && (logStr == '')){
          var info = '无日志信息可供查看';
        }
        if(logReadFlag >0 && (logStr != '')){
          var newLogNum = lineCount - logReadFlag;
          var info = '刷新成功,更新'+newLogNum+'条日志!';
          $('#logInfoTable').prepend(logStr);
        }else if(logReadFlag >0 && (logStr == '')){
          var info = '刷新成功,无日志更新!';
        }else{
          $('#logInfoTable').html(logStr);
        }
        if(op == 'search'){
          var info = '查找到'+countResult+'条日志';
        }
        $('#logTipInfo tr td').html(info);
        if((op == 'search' || op == 'refresh') &&(logReadFlag != 0 || newLogNum >0 || countResult >0)){
          setTimeout(function() {$('#logTipInfo').fadeOut(567);}, 2000);
          //操作结束后给出信息反馈，反馈自动淡出消失
        }
        else{
          $('#logTipInfo').hide();
        }
        logReadFlag = lineCount;
        console.log('closed');
      });
    }
  });
}