haeminway 9 posts
Mobile localStorage drops data silently when it fills up — but the 'saved' flag stays, so a Done check shows with no data. Which store to use for what, keeping large bodies in IndexedDB, an integrity check on open, and cutting eviction with storage.persist().
In GAS, scopes, triggers, and permissions fail silently. Miss one manifest scope and the trigger never runs. Why it fails silently, installing idempotently to dodge the 20-trigger cap, a heartbeat, and proving it ran right after install.
Apps Script goes to 100% of users the instant you promote — there's no canary. The difference between push and deploy, shipping new checks on a compat → warn → enforce ladder, telemetry that counts old clients, and the rollback command when it goes wrong.
Google Sheets silently coerces strings like '2026-06' into a Date. When save, read, and compare each compute the month differently, completion is rejected forever. What gets coerced, how to pin cells to text and guard on read, plus batch writes and formula injection.
AI built me a field-inspection app on GAS. The demo ran fine. Then one deploy button locked out every field worker, Sheets swapped my text for a date, and a green checkmark lied. The tiny bugs I fixed all day — and what to watch for before you vibe-code on GAS.
In GAS the slow part isn't JavaScript, it's service calls to Sheets and Drive. Swap in-loop getValue/setValue for batched getValues/setValues and it's tens of times faster.
A Google Sheets cell caps at 50,000 characters. Put a photo or signature in a record row as a data URL and the save breaks. Keep only metadata in the cell.
Apps Script kills any single run at 6 minutes. Design bulk jobs as chunk + cursor + time-trigger resume, or you get the half-processed-data accident.
Capturing the DOM via SVG foreignObject freezes or returns a blank image on mobile Safari and the GAS iframe. Draw to canvas directly, and download via Web Share.