Unilogger

A service to help log messages in the console or write logs to a file.

Table of Contents

API Documentation

You can find the API documentation here

Creating a Logger

To use a logger, you must first create one:

import { ConsoleLogger } from "https://deno.land/x/unilogger@v1.0.3/mod.ts";
import { FileLogger } from "https://deno.land/x/unilogger@v1.0.3/mod.ts";

const consoleLogger = new ConsoleLogger({});
const fileLogger = new FileLogger({ file: "file.log" }); // NOTE: `file` is required here, it's the filename which logging will be sent to

Using a Logger

Both logger types provide the same API methods. The only difference is, one logs to the console, one logs to a file.

Within the constructor, you can pass in level, tag_string and tag_string_fns. Both of these allow you to pass in custom data to the message if you wish to:

const logger = new ConsoleLogger({ // or FileLogger
  tag_string: "{name} | {location} |",
  tag_string_fns: {
    name() {
      return "Drashland";
    },
    location() {
      return "The Moon";
    },
  },
  level: "error", // will log any calls to `error()` and `fatal()`
});

Then calling logger.info("Hello") (or any other method) will display [INFO] Drashland | The Moon | Hello

You can check the API Reference for what is acceptable to pass to level. Below is what levels will log which types:

all: logs all messages
trace: logs trace, debug, info, warn, error, fatal
debug: logs debug, info, warn, error, fatal
info: logs info, warn, error, fatal
warn: logs warn, error, fatal,
error: logs error, fatal
fatal: logs fatal
off: does not log any messages

So this means that a logger.warn("hello") will not log if level is error.

Log message params

Log messages can take in params by specifying {} in the log message. For example:

logger.debug("Hello {}", "world")                  => Outputs "[DEBUG] Hello world"
logger.debug("Hello {} {}", "world", "world")      => Outputs "[DEBUG] Hello world world"
logger.debug("Hello {} {}", "world")               => Outputs "[DEBUG] Hello world {}"
logger.debug("Hello {} {}", "world", false)        => Outputs "[DEBUG] Hello world false"
logger.debug("Hello {} {}", "world", true)         => Outputs "[DEBUG] Hello world true"
logger.debug("Hello {} {}", "world", SomeClass)    => Outputs "[DEBUG] Hello world SomeClass"
logger.debug("Hello {} {}", "world", funcDec)      => Outputs "[DEBUG] Hello world funcDec"
logger.debug("Hello {} {}", "world", funcExp)      => Outputs "[DEBUG] Hello world funcExp"
logger.debug("Hello {}", "world", funcExp, "nope") => Outputs "[DEBUG] Hello world"