Log

The loggers in standard/log/.

A small logging surface used by Drash internally and available to you. Nothing in the request chain logs on its own.

import { ConsoleLogger } from "@drashland/drash/standard/log/ConsoleLogger.js";
import { Level } from "@drashland/drash/standard/log/Level.js";
 
const logger = ConsoleLogger.create("app", Level.Debug);
 
logger.info("Server started");

Logger

The interface the loggers implement. Six methods, one per level:

interface Logger {
  debug(...messages: unknown[]): unknown;
  error(...messages: unknown[]): unknown;
  fatal(...messages: unknown[]): unknown;
  info(...messages: unknown[]): unknown;
  trace(...messages: unknown[]): unknown;
  warn(...messages: unknown[]): unknown;
}

AbstractLogger narrows these to (message: unknown, ...replacements: unknown[]), treating the first argument as the message and the rest as substitutions into it.

Level

The severity scale. A logger writes a message when the message’s level is at or below the logger’s own.

Off silences everything; All writes everything. The default is Off, so a logger created without a level writes nothing.

AbstractLogger

Implements Logger and all six methods, plus the level filtering and message formatting. It leaves one method abstract:

protected abstract write(...messages: unknown[]): unknown;

Subclass it and implement write() to send messages somewhere other than the console. ConsoleLogger implements it as write(level, message, replacements).

Formatting pads the logger name to 25 characters with dots, so lines from differently-named loggers align.

ConsoleLogger

AbstractLogger with write() calling console.log().

ConsoleLogger.create(name, level?)

static create(name: string, level: LogLevel = Level.Off): ConsoleLogger

The default is the thing to watch. ConsoleLogger.create("app") produces a logger that silently discards every message.

GroupConsoleLogger

The same surface, for grouping related messages under one heading. Also exposes Level.

Notes

These loggers are deliberately minimal, and Drash does not require you to use them. For production logging, the Error Handling page shows the shape to aim for — a real logging library in your .catch() block, with the message and the error object going to different levels.