原生node.js实现日志功能

node.js实现简单规范日志打印功能

1.先新建文件夹，使用npm init --yes，初始化package.json

npm init --yes

2.新建实现日志功能的JS文件,nodeLog.js

3.引入node.js的文件操作模块

const fs = require("fs");

4.引入node自带的fs模块、path模块。因为规范的日志需要时间戳，所以这里引入时间戳工具。安装node-datetime,并引入

npm i node-datetime -S

const datetime = require("node-datetime");

5.编写代码

所有代码如下

// nodeLog.js
const fs = require("fs");
const path = require("path");
const datetime = require("node-datetime");


class nodeLog{

  constructor(userName = "admin"){
    this.user = userName;
  }

  writeMessage(msg){
    var pwd = process.cwd();
    var fileName = `${path.resolve(pwd,"./logs")}.txt`;
    fs.appendFileSync(fileName, msg+"\n");    
  }

  getDate(){
    var nowTime = datetime.create();
    var nowTimeFormatted  = nowTime.format('Y/m/d H:M:S');
    return nowTimeFormatted;
  }

  printLog(typeName = "INFO",msg = ""){
    var logStr = `${this.getDate()} [ ${typeName}  -  ${this.user} ]${msg}`;
    console.log(logStr);
    this.writeMessage(logStr);
  }  

  all(msg){
    this.printLog("ALL",msg);
  }

  trace(msg){
    this.printLog("TRACE",msg);
  }

  debug(msg){
    this.printLog("DEBUG",msg);
  }
  
  info(msg){
    this.printLog("INFO",msg);
  }

  warn(msg){
    printLog("WARN",msg);
  }

  error(msg){
    printLog("ERROR",msg);
  }

  fatal(msg){
    printLog("FATAL",msg);
  }

  off(msg){
    printLog("OFF",msg);
  }


}

module.exports = nodeLog;

// useLog.js
const nodeLog = require("./nodeLog.js");

const NLog0 = new nodeLog();
NLog0.info("login in");
NLog0.info("login out");

const NLog1 = new nodeLog("user1");
NLog1.info("login in");
NLog1.info("login out");

const NLog2 = new nodeLog("user2");
NLog2.info("login in");
NLog2.info("login out");

文件目录如下

6.终端执行node useLog.js,会输出log.txt文件作为打印日志。同时也会在终端打印。