This article will introduce to you how to use the Winston library to build a simple logging function in Node.js. I hope it will be helpful to everyone!
Winston is one of the powerful and flexible Node.js
open source log libraries. In theory, Winston is a logger that can record all information. This is a highly intuitive tool that is easy to customize. The logic behind it can be adjusted by changing a few lines of code. It makes logging to persistent storage locations such as databases or files simple and easy. [Recommended learning: "nodejs Tutorial"]
Winston Provides the following functions:
The practice code will add the logging function to the projectpretender-service, and install the dependencies:
npm install winston --save
The next step is to initialize logger
, since there is already a logger.js
file in the project, create another winstonLogger.js
here, the code is as follows:
const { createLogger, format, transports } = require("winston"); module.exports = createLogger({ transports: [ new transports.File({ filename: "logs/server.log", level: "info", format: format.combine( format.timestamp({ format: "MMM-DD-YYYY HH:mm:ss" }), format.align(), format.printf( (info) => `${info.level}: ${[info.timestamp]}: ${info.message}` ) ), }), ], });
Passed Call the createLogger
function in the winston
library to initialize the logger. In the transports
object, you can provide a filename to store the logs in a file. By default, logging is unformatted and printed as a JSON string with two parameters, the log message and the level.
Next, modify the previous logger
and add the winston
logger. Please refer to the code for the specific modification method. Here is how to use it:
const winlogger = require("./winstonLogger"); winlogger.info("日志内容");
After executing the program, the corresponding log file can be generated in the root directory logs/server.log
You can also change the log level, Modify logger
and only use winston
in console.error
mode:
records the database connection Error messages, the above information is for demonstration only.
winston
Allows setting multiple transport
, change createLogger# in
winstonLogger.js ## The function is as follows:
const { createLogger, format, transports } = require("winston"); module.exports = createLogger({ format: format.combine( format.timestamp({ format: "MMM-DD-YYYY HH:mm:ss" }), format.align(), format.printf((i) => `${i.level}: ${[i.timestamp]}: ${i.message}`) ), transports: [ new transports.File({ filename: "logs/info.log", level: "info", format: format.combine( format.printf((i) => i.level === "info" ? `${i.level}: ${i.timestamp} ${i.message}` : "" ) ), }), new transports.File({ filename: "logs/error.log", level: "error", }), ], });
error.log and
info.log files, because in
logger
info is not set in , so the content of
info.log is empty, and the content of
error.log is the same as above.
winston Allows the setting of multiple
loggers. In actual projects, a logger can be created for each module
logger , the following code creates a user logger and login verification recorder:
const { createLogger, format, transports } = require("winston"); const customFormat = format.combine( format.timestamp({ format: "MMM-DD-YYYY HH:mm:ss" }), format.align(), format.printf((i) => `${i.level}: ${[i.timestamp]}: ${i.message}`) ); const globalLogger = createLogger({ format: customFormat, transports: [ new transports.File({ filename: "logs/info.log", level: "info", format: format.combine( format.printf((i) => i.level === "info" ? `${i.level}: ${i.timestamp} ${i.message}` : "" ) ), }), new transports.File({ filename: "logs/error.log", level: "error", }), ], }); const authLogger = createLogger({ transports: [ new transports.File({ filename: "logs/authLog.log", format: customFormat, }), ], }); module.exports = { globalLogger: globalLogger, authLogger: authLogger, };
globalLogger and an authentication logger
authLogger, corresponding modification
logger.js:
const { globalLogger } = require("./winstonLogger"); globalLogger.error(message);
Winston related dependency library.
npm install winston-daily-rotate-file --save
winstonLogger.js file:
const { createLogger, format, transports } = require("winston"); require("winston-daily-rotate-file"); const customFormat = format.combine( format.timestamp({ format: "MMM-DD-YYYY HH:mm:ss" }), format.align(), format.printf((i) => `${i.level}: ${[i.timestamp]}: ${i.message}`) ); const defaultOptions = { format: customFormat, datePattern: "YYYY-MM-DD", zippedArchive: true, maxSize: "20m", maxFiles: "14d", }; const globalLogger = createLogger({ format: customFormat, transports: [ new transports.DailyRotateFile({ filename: "logs/info-%DATE%.log", level: "info", ...defaultOptions, }), new transports.DailyRotateFile({ filename: "logs/error-%DATE%.log", level: "error", ...defaultOptions, }), ], }); const authLogger = createLogger({ transports: [ new transports.DailyRotateFile({ filename: "logs/authLog-%DATE%.log", ...defaultOptions, }), ], }); module.exports = { globalLogger: globalLogger, authLogger: authLogger, };
Winston has been introduced. The above can basically meet the needs of daily projects.
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