custom level not work in typescript

Please tell us about your environment:

• winston version?
  • winston@2
  • winston@3
• _node -v outputs:_v8.12.0
• Operating System? macOS
• Language? | TypeScript 3.1.3

What is the problem?

custom level not work in typescript 3.1.3

code

import winston from 'winston';

const myCustomLevels: winston.config.AbstractConfigSetLevels = {
  foo: 0,
  bar: 1,
  baz: 2,
  foobar: 3
};

const customLevelLogger = winston.createLogger({
  levels: myCustomLevels,
  transports: [
    new winston.transports.Console({
      level: 'foobar'
    })
  ]
});
//  [ts] Property 'foobar' does not exist on type 'Logger'.
customLevelLogger.foobar('some foobar level-ed message');

[jensbodal]

Another alternative is to just extend the winston.Logger interface and then cast the result of createLogger to your interface.

import winston from 'winston';

const myCustomLevels: winston.config.AbstractConfigSetLevels = {
  foo: 0,
  bar: 1,
  baz: 2,
  foobar: 3
};

interface CustomLevels extends winston.Logger {
  foo: winston.LeveledLogMethod;
  bar: winston.LeveledLogMethod;
  baz: winston.LeveledLogMethod;
  foobar: winston.LeveledLogMethod;
}

const customLevelLogger: CustomLevels = <CustomLevels>winston.createLogger({
  levels: myCustomLevels,
  transports: [
    new winston.transports.Console({
      level: 'foobar'
    })
  ]
});

customLevelLogger.foobar('some foobar level-ed message');

[evankennedy]

It would be even better if each logger could infer levels from the createLogger call. That means if we exclude certain common levels from the levels config, we will get the proper compile-time error if we try calling that.

For example, we could make it infer the levels in this example:

const logger = winston.createLogger({
  levels: { custom: 0 },
});

// works:
logger.custom('stuff');
logger.log('custom', 'stuff');

// compile error:
logger.info('stuff');
logger.log('info', 'stuff');

I’m happy to work on a PR when I get some free time.

---

Edit: I realize maybe this can’t be done since Winston can be augmented on the fly with .configure() 😫