@viktorbarzin/log

A JSON-lines logger for the platform's log contract: one object per line on stderr with ts (Python isoformat, +00:00), level, logger, msg, then the call's extras (which never overwrite those four keys), then exc for an error. No dependencies; works on Bun and Node.

import { getLogger, installJsonConsole } from "@viktorbarzin/log";

const log = getLogger("myapp.sync");
log.info("sync served", { user: "someone", lists: 3 });
log.exception("sync failed", err, { path: "/api/sync" });

installJsonConsole(); // console.* from the framework becomes JSON lines too (logger "console")

{"ts":"2026-10-16T04:05:06.789000+00:00","level":"INFO","logger":"myapp.sync","msg":"sync served","user":"someone","lists":3}

API

| Export | | |---|---| | getLogger(name) | debug, info, warning, error, exception(msg, err, extra?), record(level, msg, extra?, err?) | | parseLogLevel(raw) | WARN → WARNING; unknown or unset → INFO | | setLogLevel(level) | the threshold; starts from LOG_LEVEL | | setLogSink(sink) | send lines elsewhere (tests); returns a restore function | | installJsonConsole(target?) | route console.* through the logger; an Error argument goes under exc; returns a restore function | | formatRecord, pythonIsoTimestamp | the formatting, exported for tests |

The sink and threshold are one per process (kept on globalThis), so a server bundled twice still logs through one sink. LOG_LEVEL is the only environment variable read.