Merge pull request #1354 from hotwired/adapter-prefetching

Verify with the browser adapter before initiating link prefetching

src/core/drive/navigator.js

@@ -117,6 +117,17 @@ export class Navigator {
     }
   }
 
+  // Link prefetching
+
+  linkPrefetchingIsEnabledForLocation(location) {
+    // Not all adapters implement linkPrefetchingIsEnabledForLocation
+    if (typeof this.adapter.linkPrefetchingIsEnabledForLocation === "function") {
+      return this.adapter.linkPrefetchingIsEnabledForLocation(location)
+    }
+
+    return true
+  }
+
   // Visit delegate
 
   visitStarted(visit) {

src/core/native/browser_adapter.js

@@ -72,6 +72,12 @@ export class BrowserAdapter {
 
   visitRendered(_visit) {}
 
+  // Link prefetching
+
+  linkPrefetchingIsEnabledForLocation(location) {
+    return true
+  }
+
   // Form Submission Delegate
 
   formSubmissionStarted(_formSubmission) {

src/core/session.js

@@ -232,7 +232,8 @@ export class Session {
   canPrefetchRequestToLocation(link, location) {
     return (
       this.elementIsNavigatable(link) &&
-        locationIsVisitable(location, this.snapshot.rootLocation)
+      locationIsVisitable(location, this.snapshot.rootLocation) &&
+      this.navigator.linkPrefetchingIsEnabledForLocation(location)
     )
   }
 

src/tests/unit/native_adapter_support_tests.js

@@ -11,6 +11,7 @@ class NativeAdapterSupportTest {
   finishedVisitRequests = []
   startedFormSubmissions = []
   finishedFormSubmissions = []
+  linkPrefetchRequests = []
 
   // Adapter interface
 
@@ -53,6 +54,10 @@ class NativeAdapterSupportTest {
   }
 
   pageInvalidated() {}
+
+  linkPrefetchingIsEnabledForLocation(location) {
+    this.linkPrefetchRequests.push(location)
+  }
 }
 
 let adapter
@@ -204,3 +209,13 @@ test("visit follows redirect and proposes replace visit to adapter", async () =>
   assert.equal(visit.location, redirectedLocation)
   assert.equal(visit.options.action, "replace")
 })
+
+test ("link prefetch requests verify with adapter", async () => {
+  const locatable = window.location.toString()
+
+  Turbo.navigator.linkPrefetchingIsEnabledForLocation(locatable)
+  assert.equal(adapter.linkPrefetchRequests.length, 1)
+
+  const [location] = adapter.linkPrefetchRequests
+  assert.equal(location, locatable)
+})