@jsvision/core / createLogger

Function: createLogger()

createLogger(options?): Logger

Defined in: safety/logger.ts:249

Create a screen-safe logger.

Enablement. Off unless you pass enabled: true, set JSVISION_DEBUG=1, or choose sink: 'ring'. A disabled logger is a pure no-op (every method returns without writing and entries() is empty), so a normal run writes nothing.

Sink selection (sink: 'auto', the default): a file if a path is set (options.path or the JSVISION_LOG env var); else stderr when it is a different device from the screen; else the in-memory ring buffer.

Screen safety. Construction throws LoggerConfigError if the chosen sink would resolve to the terminal's own output stream, so a misconfigured logger can never corrupt your rendered UI.

Parameters

options?

LoggerOptions = {}

Optional configuration; env vars supply the defaults.

Returns

Logger

A Logger. It is a no-op when not enabled.

Throws

LoggerConfigError when the resolved sink targets the terminal's output stream.

Example

import { createLogger } from '@jsvision/core';

// Enable via env (JSVISION_DEBUG=1) and log to a file (JSVISION_LOG=/tmp/app.log):
const log = createLogger();
log.info('host', 'started', { cols: 120, rows: 40 });

// Or capture in memory for a diagnostics dump (always enabled):
const ring = createLogger({ sink: 'ring' });
ring.debug('input', 'key pressed');
console.error(ring.entries());
ring.close();