node错误处理与日志记录的实现

// Error对象自带的属性
Error.captureStackTrace

// 如何使用captureStackTrace
var obj = {
  message: 'something is wrong'
}

Error.captureStackTrace(obj)

throw obj  // 此时会抛出obj对象的message内信息

try{
  throw new Error('oh no')
}catch(e){
  console.log(e)
}

function foo(params, cb){
  const error = new Error('something is wrong')
  if(error) cb(error)
}

async function foo(){
  try{
    await bar()
  }catch(e){
    console.log(e)
  }
}

async function bar(){
  throw new Error('async function got wrong)
}

foo()

// 基本错误类型
class HttpBaseError extends Error {
 constructor(httpStatusCode, httpMsg, errCode, msg) {
  super(`HTTP ERROR: ${msg}`);
  this.httpStatusCode = httpStatusCode;
  this.httpMsg = httpMsg;
  this.errCode = errCode;
 }
}

try {
// 直接抛出定义好的错误即可
 throw new HttpBaseError(404, '资源不存在', 10000, 'resouse is not found');
} catch (e) {
 console.log(e.message);
 console.log(e.httpStatusCode);
 console.log(e.httpMsg);
 console.log(e.errCode);
}

// 一个参数错误类型
const ERROR_CODE = 40000  // 错误码
class HttpRequestParamError extends HttpBaseError {
  constructor(paramName, desc, msg) {
    super(200, desc, ERROR_CODE, `${paramName} wrong: ${msg}`)
  }
}

// error handler
function handler(options) {
  return function (err, req, res, next) {
    if (err instanceof HttpRequestParamError) {  // 这里对不同的错误做不同的处理
      console.log('http request error')
      res.statusCode = err.httpStatusCode
      res.json({
        code: err.errCode,
        msg: err.httpMsg
      })
    } else {
      // 设定之外的错误，把管理权向外移交
      next(err)
    }
  }
}

function unKnowErrorHandler(options) {
  return function (err, req, res, next) {
    console.log(err)
    res.json({
      code: 99999,
      msg: 'unKnow error'
    })
  }
}

const winston = require('winston')

const logger = winston.createLogger({
  transports: [
    new winston.transports.Console(),
    new winston.transports.File({
      name: 'info_logger',  // log名称
      filename: 'logs/info.log',  // 日志记录文件地址
      level: 'info' // 设置log的类型
    }),
    // 第二个logger，记录error级别的log
    new winston.transports.File({
      name: 'error_logger',
      filename: 'logs/error.log',
      level: 'error'
    })
  ]
});

// error级别比info要高，error.log文件只会记录error日志
logger.error('first error log with winston')
// info文件内会记录info级别的log和比info级别高的log，比如error
logger.info('first info log with winston')

const {
  createLogger,
  format,
  transports
} = require('winston');
const {
  combine,
  timestamp,
  label,
  prettyPrint
} = format;
require('winston-daily-rotate-file')


var transport = new(transports.DailyRotateFile)({
  filename: './logs/app-%DATE%.log',
  datePattern: 'YYYY-MM-DD-HH',
  maxSize: '20m',
  maxFiles: '14d',
  format: combine(
    label({
      label: 'right meow!'
    }),
    timestamp(),
    prettyPrint()
  ),
});
transport.on('rotate', function (oldFilename, newFilename) {});

var logger = createLogger({
  transports: [
    transport
  ]
});

logger.info('Hello World!');