node日志库winston

winstonnode日志库，地址 npm install winston。1.基本使用const winston = require(‘winston’)// 配置日志系统const logger = winston.createLogger({ //输出日志等级小于该设定值时输出,“info,erro,verbose“等 level：‘info’, //日志等级定义，默认为自带等级设定 levels: winston.config.npm.levels, //对输出信息进行格式化 format: winston.format.json, //日志信息输出到哪里，例如某个文件或者命令行,默认[] transports:[ new winston.transports.Console(), new winston.transports.File({ filename: ‘combined.log’ }) ], //exceptions 是否会出导致 process.exit, 设为false不会 exitOnError:true, //为true时所有日志不输出 silent:false})//日志输出logger.error(‘Hello again distributed logs’);2. levels日志等级默认日志等级//winston.config.npm.level{ error: 0, warn: 1, info: 2, verbose: 3, debug: 4, silly: 5 }自定义日志等级const myCustomLevels = { levels: { foo: 0, bar: 1, baz: 2, foobar: 3 }, colors: { foo: ‘blue’, bar: ‘green’, baz: ‘yellow’, foobar: ‘red’ }};const logger = winston.createLogger({ levels: myCustomLevels.levels });logger.foobar(‘some foobar level-ed message’);3. format格式化Format模块的输入是一个参数名为info的对象。const info = { level: ‘info’, message: ‘hey, log something’, meta:{} //其他参数}Format的过程就是对上述对象进行变换产生新的info对象的过程，自定义一个transform如下：const volume = format((info, opts) => { if (opts.yell) { info.message = info.message.toUpperCase(); } else if (opts.whisper) { info.message = info.message.toLowerCase(); } return info; // return false将过滤掉该info});当要应用多个transform时，需要使用format.combine函数将多个变换组合起来，有点类似函数式编程中的compose。const { combine, timestamp, label } = format;const labelTimestamp = combine( label({ label: ‘right meow!’ }), timestamp());常用的transformColorizecolorize({ //各种日志的颜色 colors: { info: ‘blue’,error:‘red’ }, //颜色应用的范围 level:true , all: false, message: true})Printf自定义输出const myFormat = printf(( {level, message, label, timestamp}) =>{ return ${timestamp} [${label}] ${level}: ${message}})Timestamp添加时间戳format.timestamp();更多4. transports输出添加多个transportsconst logger = winston.createLogger({ transports: [ new winston.transports.Console(), new winston.transports.File({ filename: ‘combined.log’, level: ‘info’ //低于该等级的日志输出 }), new winston.transports.File({ filename: ’errors.log’, level: ’error’ }) ]});移除之前的transportconst combinedLogs = logger.transports.find(transport => { return transport.filename === ‘combined.log’});logger.remove(combinedLogs);自定义transportconst Transport = require(‘winston-transport’);const util = require(‘util’);//// Inherit from winston-transport so you can take advantage// of the base functionality and .exceptions.handle().//module.exports = class YourCustomTransport extends Transport { constructor(opts) { super(opts); // // Consume any custom options here. e.g.: // - Connection information for databases // - Authentication information for APIs (e.g. loggly, papertrail, // logentries, etc.). // } log(info, callback) { setImmediate(() => { this.emit(’logged’, info); }); // Perform the writing to the remote service callback(); }};