Logging

Structured-enough logging without pulling in a framework. One logger, one or more providers, optional formatters.

import {
  Logger,
  LogLevel,
  ConsoleProvider,
  FileProvider,
  JSONFormatter,
} from "semola/logging";

Quick start

const log = new Logger("api", [new ConsoleProvider()]);

log.debug("handshake");
log.info("server started");
log.warning("slow query");
log.error("request failed");
log.critical("cannot reach database");

The first argument is a prefix shown on every line. Pass several providers to fan out:

const log = new Logger("worker", [
  new ConsoleProvider(),
  new FileProvider("./logs/worker.log"),
]);

Levels and format

LogLevel enumerates severity. Providers accept options (level filters, formatters). JSONFormatter emits JSON lines; date helpers (isoDateFormat, isoDateTimeFormat, dmyFormat, mdyFormat) help with timestamps.

Extend AbstractLogger or LoggerProvider if you need a custom sink. Most apps only need Logger + ConsoleProvider.