Winston simple format example

index.js

const { createLogger, format, transports } = require('winston');

let test = {};

test.simple = () => {
  const logger = createLogger({
    format: format.simple(),
    transports: [new transports.Console()]
  });
  logger.info('Hello world!');
};

test.splat = (arg) => {
  const logger = createLogger({
    format: format.combine(
      format.splat(),
      format.simple()
    ),
    transports: [new transports.Console()]
  });
  logger.info('int argument: %d, memoryUsage: %o', parseInt(arg), process.memoryUsage());
};

test.pretty = (arg) => {
  const logger = createLogger({
    format: format.combine(
      format.splat(),
      format.prettyPrint()
    ),
    transports: [new transports.Console()]
  });
  logger.info('memoryUsage: %o', process.memoryUsage());
};

if (require.main === module) {
  const name = process.argv[2];
  const args = process.argv.slice(3);
  if (!name) {
    test.simple();
  } else {
    test[name].apply(null, args);
  }
}

output.txt

$ node index.js simple
info: Hello world!


$ node index.js splat 123
info: int argument: 123, memoryUsage: { rss: 24399872,
  heapTotal: 11378688,
  heapUsed: 7998560,
  external: 154088 }


$ node index.js pretty 123
{ rss: 24231936,
  heapTotal: 11378688,
  heapUsed: 7992544,
  external: 154088,
  level: 'info',
  message: 'memoryUsage: { rss: 24231936,\n  heapTotal: 11378688,\n  heapUsed: 7992544,\n  external: 154088 }',
  [Symbol(level)]: 'info',
  [Symbol(splat)]:
   [ { rss: 24231936,
       heapTotal: 11378688,
       heapUsed: 7992544,
       external: 154088 } ] }

package.json

{
  "name": "winston-simple-example",
  "version": "1.0.0",
  "description": "Winston simple format example",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "[email protected]",
  "license": "ISC",
  "dependencies": {
    "winston": "^3.0.0"
  }
}