Events, fetch, and real form submission contracts. The three lessons in this section follow a single inspection workflow, so the request, browser behavior, server decision, and visible result can be checked together.
Lessons
- DOM events: enhance a working control without losing its baseline — Attach one handler to a form that already submits a useful request.
- Fetch requests: separate HTTP failure, transport failure, and cancellation — Check response status, bound waiting time, and discard obsolete results.
- Form submission: validate on the server and return field errors — Preserve submitted values while rejecting records that break the stored contract.
- Cross-origin requests: read CORS as a browser access policy — Allow only intended browser origins without mistaking CORS for authentication.
- Responsive interaction: preserve content and control order — Change layout across widths without hiding the only path to an action.
Continue across the track
Requests and Browser Foundations; State and Trust; Quality and Release; Web Technology: Projects; Web Development: Quizzes.
Broader connections
Frontend Application Architecture; Media and Live Updates; Offline and Device Capabilities.