logger.js

// VanillaJS Logger
// 
// NOTE: You probably shouldn't use this in production... you've been warned.
let logger = {};

// Log levels
// debug=0, info=1, log=2, warn=3, error=4
const LOG_LEVELS = [
  "debug",
  "info",
  "log",
  "warn",
  "error",
];
const logComponent = "api.logger";

// Set log level
logger.setLogLevel = function(logLevel="warn") {
  console[logLevel]("[%s] log level: %s", logComponent, logLevel);
  let limit = LOG_LEVELS.indexOf(logLevel);
  LOG_LEVELS.filter( function(level, index) { if (index < limit) { 
    console[logLevel]("[%s] disabling console.%s()", logComponent, level);
    console[level] = function() {};
  }});
};

// Timestamp generator
logger.timestampISO = function() {
  let now = new Date();
  return now.toISOString();
};

// Custom JSON Logger
logger.log = function(msg, level="log") {
  console[level](JSON.stringify({
    ts: logger.timestampISO(),
    msg: msg,
  },null,0))
};

export default logger;

Is this completely insane in the-year-of-our-lord 2023?!

I've used this in two serverless projects now. Simply doing a import logger from ./logger.js and running logger.setLogLevel("warn") gives me a one-liner for "muting" any rogue console.log() debug code. I usually also set log level from an environment variable (e.g. logger.setLogLevel(env.LOG_LEVEL)), so I get debug logging in development and no debug logging in production.

Is this the oldest news ever? I've been obsessed with reducing my third-party deps lately, so when it came to logging I was like "Y U NO console.whatever()?"

This even includes a little logger.log() helper, but half the time I forget it's there and just console.warn() or console.error() and ITSFINE.GIF. Anyway, hopefully someone will sanity check me and explain why I really can't get away with a <50 LOC vanilla JS logger, LOL.