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Output Console as a production logger — window.JUSTZIX in practice

15 May 2026 · by JustZix Team

Diagnosing a page with console.log needs DevTools open — and that takes half the screen and vanishes on every reload. window.JUSTZIX logs into the Output Console window, which is part of the page: it stays where you put it, and you see it without F12.

Two different APIs

JustZix gives rule code two global objects — easy to confuse:

• window.JZ — drives actions (JZ.click and friends).
• window.JUSTZIX — a logger. Writes entries to the Output Console window.

This article is about the second one.

The logger methods

JUSTZIX.log('a plain entry');
JUSTZIX.info('information');
JUSTZIX.warn('a warning');
JUSTZIX.error('an error');
JUSTZIX.debug('a diagnostic detail');

Each level has its own color in the Output Console and can be filtered. There are also aliases __JUSTZIX__ and JZ.log/.warn/... — in case the page has its own variable named JUSTZIX.

Why not plain console.log

• No DevTools. The Output Console renders on the page. You do not have to open F12 or keep it open.
• It survives in view. A pinned Output window stays in the corner of the tab — you see logs out of the corner of your eye, all the time.
• Filters and search. You filter levels and search entries — built into the window.

The Output Console also captures the page's own console.log and uncaught errors — but JUSTZIX.* is your own channel, visually separated from the page's noise.

Pattern — checkpoints in a rule

JUSTZIX.info('Cart rule — start');
const items = document.querySelectorAll('.cart-item');
JUSTZIX.log('Items in cart: ' + items.length);
if (!items.length) JUSTZIX.warn('Empty cart — selector still current?');

The rule narrates what it does. When it stops working, the Output Console shows exactly which step — with no guessing.

Pitfalls

• Logs in a loop. A JUSTZIX.log in a scroll handler or a MutationObserver floods the window. Log events, not every frame.
• The debug level can be hidden. The Output Console filters debug by default — if you do not see an entry, check the level filter.

See also

• Output Console — the full window write-up
• Output Console catches errors — what else lands in the window
• Rules resilient to DOM changes — the logger as an early-warning system

Install JustZix — and log without opening DevTools.