https://foxipa.com/en/web-apis/learn/beacon/ A 17-part Beacon API learning path — from fire-and-forget fundamentals and the queueing boolean through the 64 KiB quota, page-lifecycle delivery, CORS, service workers, and fetchLater() — with runnable, spec-verified examples on every page. Hugo en-US https://foxipa.com/en/web-apis/learn/beacon/fire-and-forget/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/fire-and-forget/ Why teardown-time telemetry is hard, what navigator.sendBeacon() promises (queueing, not delivery), and the fixed fetch recipe every beacon request carries. https://foxipa.com/en/web-apis/learn/beacon/where-it-runs/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/where-it-runs/ Navigator versus WorkerNavigator, the two-step feature detection that covers every runtime, and an honest separation of spec maturity from shipping folklore. https://foxipa.com/en/web-apis/learn/beacon/signature-and-boolean/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/signature-and-boolean/ The real sendBeacon IDL with no third parameter, the only two conditions that throw, and what false actually means — demonstrated live. https://foxipa.com/en/web-apis/learn/beacon/payloads-and-content-type/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/payloads-and-content-type/ Every type sendBeacon's data parameter accepts, the Web IDL stringify truth for odd values, and the fixed Content-Type mapping observed live through Request. https://foxipa.com/en/web-apis/learn/beacon/the-cors-trap/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/the-cors-trap/ The safelist rule that decides a beacon's CORS mode, what opaque responses cost, why refused preflights are invisible, and the JSON-Blob story sorted from folklore. https://foxipa.com/en/web-apis/learn/beacon/cors-safe-payloads/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/cors-safe-payloads/ The JSON-as-text/plain envelope, form encoding for flat events, and a unified payload builder that measures what it sends in real bytes. https://foxipa.com/en/web-apis/learn/beacon/the-64kib-quota/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/the-64kib-quota/ The Fetch §4.6 algorithm verbatim, what it counts (bodies only), when slots release, and the myths — simulated live at the byte level. https://foxipa.com/en/web-apis/learn/beacon/quota-aware-queue/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/quota-aware-queue/ Why ReadableStream bodies always throw under keepalive, and the batching queue recipe that moves many events through one pool slot. https://foxipa.com/en/web-apis/learn/beacon/page-lifecycle/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/page-lifecycle/ The spec's MUST-flush-on-hidden guarantee parsed clause by clause, state-versus-event reasoning, ordering, and mobile reality. https://foxipa.com/en/web-apis/learn/beacon/lifecycle-flusher/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/lifecycle-flusher/ One flush per hidden transition, bfcache restores identified precisely via persisted pageshow, and the layered case against unload. https://foxipa.com/en/web-apis/learn/beacon/server-side-cors/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/server-side-cors/ What forced credentials:include demands from the server, the preflight trio, the 204 habit, and a framework-free Node collector. https://foxipa.com/en/web-apis/learn/beacon/service-worker-interception/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/service-worker-interception/ The keepalive-POST-empty-destination detection triple with its honest false positives, and the buffer-then-re-issue patterns that never lose data. https://foxipa.com/en/web-apis/learn/beacon/workers-and-keepalive/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/workers-and-keepalive/ The keepalive flag's specification, the fetch-groups exemption that lets requests outlive their context, and the exact capability trade against sendBeacon. https://foxipa.com/en/web-apis/learn/beacon/sendbeacon-vs-fetch-keepalive/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/sendbeacon-vs-fetch-keepalive/ One decision function from runtime and capability, the hybrid sender with its discriminated return, and the famous one-line fallback — with the shared-pool trap that makes it a capability answer only. https://foxipa.com/en/web-apis/learn/beacon/real-world-patterns/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/real-world-patterns/ Batching, lifecycle flushes, bfcache-tagged restores, stable A/B assignment, and IndexedDB persistence with save-before-clear ordering — one vanilla SDK. https://foxipa.com/en/web-apis/learn/beacon/fetchlater/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/fetchlater/ The real FetchLaterResult IDL, the five throwing gates, whole-request quota accounting against the per-origin cap, and when deferred beats immediate. https://foxipa.com/en/web-apis/learn/beacon/testing-and-reference/ Sun, 27 Sep 2026 00:00:00 +0000 https://foxipa.com/en/web-apis/learn/beacon/testing-and-reference/ The Playwright interception fixture the series was validated with, what DevTools can show, and every load-bearing fact on one card with its spec anchor.