LabsLab 08 · Intermediate · 25 min
Files and cancellable work
Import bounded CSV atomically, export escaped fields, and cancel asynchronous server work with progress.
Atomic CSV import
At most 1 MiB and 1,000 rows. Dates use yyyy-MM-dd. Export quotes fields and prefixes formula-like summaries with an apostrophe for spreadsheet safety; import removes that one apostrophe, so a round trip keeps every summary unchanged. Blank lines are ignored.
Five sample rows loaded.
| Date | °C | Summary |
|---|---|---|
| 1/1/2026 | 18 | Freezing |
| 1/2/2026 | 3 | Warm |
| 1/3/2026 | -10 | Freezing |
| 1/4/2026 | 12 | Warm |
| 1/5/2026 | 12 | Hot |
Cancellable work
Process 100 simulated steps, 50 ms each, on the browser. Work belongs to this page and stops when you leave. For durable work, the deployment guide explains the next step: a hosted queue and persisted job state.
Idle
Why it works
The entire import is parsed and validated before replacing the sample. Processing belongs to this component and is canceled when it is disposed; it is not a durable job queue.
Try it yourself
Export, edit a quoted summary, and import it. Try an invalid row. Start processing and cancel halfway through.