Refactor site generation into a modular content pipeline

dev-reload.js

@@ -0,0 +1,39 @@
+// Keep only the newest generation's result visible to the browser.
+export const createRegenerationQueue = ({ generate, onSuccess, onError, delay = 100 }) => {
+  let timer
+  let running = false
+  let revision = 0
+  let closed = false
+
+  const run = async () => {
+    if (closed || running) return
+    running = true
+    const started = revision
+    try {
+      await generate()
+      if (!closed && started === revision) onSuccess()
+    } catch (error) {
+      if (!closed && started === revision) onError(error)
+    } finally {
+      running = false
+      if (!closed && started !== revision) schedule()
+    }
+  }
+
+  const schedule = () => {
+    clearTimeout(timer)
+    timer = setTimeout(run, delay)
+  }
+
+  return {
+    request() {
+      if (closed) return
+      revision += 1
+      schedule()
+    },
+    close() {
+      closed = true
+      clearTimeout(timer)
+    },
+  }
+}