A lightweight logging library exploring a new paradigm for handling excluded logs. It's use is designed for both application developers and library developers. Optional chaining syntax is used to handle excluding logs, allowing for more efficient logging, especially when dealing with expensive to compute log messages.

The log level is set once at the beginning of the application via an environment variable or a meta tag and cannot be changed during runtime. The default log level for jsr:@doctor/log/app is info and the default log level for jsr:@doctor/log/lib is none. If the environment variable is not set; set to an invalid value; or permissions to read the variable is not granted from the start, this library will fall back to its default log level.

This library makes optional use of the Temporal API if it is available for its timestamps, otherwise falls back to Date.

This library works in Deno, NodeJS and the browser. To use it in the browser, a meta tag should exist before this code runs.

LOG_LEVEL=4 deno run -E='LOG_LEVEL' --unstable-temporal main.ts <meta name="doctor/log" data-name="LOG_LEVEL" data-level="4">

import { terminal } from "@doctor/log/app";

terminal.info?.("Hello World!");
// ~[TIMESTAMP] [INFO] Hello World!

ABC_XYZ=4 deno run -E='ABC_XYZ' --unstable-temporal lib.ts <meta name="doctor/log" data-name="ABC_XYZ" data-level="4">

import { createTerminal } from "@doctor/log/lib";

const terminal = await createTerminal("my-app", "ABC_XYZ");
terminal.info?.("Hello World!");
// ~[TIMESTAMP] [INFO] [my-app] Hello World!