Enable InstaClick by default

src/observers/link_prefetch_observer.js

@@ -1,4 +1,5 @@
 import {
+  dispatch,
   doesNotTargetIFrame,
   getLocationForLink,
   getMetaContent,
@@ -58,7 +59,7 @@ export class LinkPrefetchObserver {
   }
 
   #tryToPrefetchRequest = (event) => {
-    if (getMetaContent("turbo-prefetch") !== "true") return
+    if (getMetaContent("turbo-prefetch") === "false") return
 
     const target = event.target
     const isLink = target.matches && target.matches("a[href]:not([target^=_]):not([download])")
@@ -134,7 +135,16 @@ export class LinkPrefetchObserver {
   #isPrefetchable(link) {
     const href = link.getAttribute("href")
 
-    if (!href || href === "#" || link.getAttribute("data-turbo") === "false" || link.getAttribute("data-turbo-prefetch") === "false") {
+    if (!href || href.startsWith("#") || link.getAttribute("data-turbo") === "false" || link.getAttribute("data-turbo-prefetch") === "false") {
+      return false
+    }
+
+    const event = dispatch("turbo:before-prefetch", {
+      target: link,
+      cancelable: true
+    })
+
+    if (event.defaultPrevented) {
       return false
     }
 

src/tests/fixtures/hover_to_prefetch.html

@@ -27,6 +27,8 @@
       >Won't prefetch when hovering me</a>
     <a href="/src/tests/fixtures/prefetched.html" id="anchor_with_turbo_false" data-turbo="false"
       >Won't prefetch when hovering me</a>
+    <a href="/src/tests/fixtures/prefetched.html" id="anchor_with_remote_true" data-remote="true"
+      >Won't prefetch when hovering me</a>
     <a href="/src/tests/fixtures/hover_to_prefetch.html" id="anchor_for_same_location"
       >Won't prefetch when hovering me</a>
     <a href="/src/tests/fixtures/prefetched.html?foo=bar" id="anchor_for_same_location_with_query"

src/tests/functional/link_prefetch_observer_tests.js

@@ -62,6 +62,22 @@ test("it doesn't prefetch the page when link has data-turbo=false", async ({ pag
   await assertNotPrefetchedOnHover({ page, selector: "#anchor_with_turbo_false" })
 })
 
+test("allows to cancel prefetch requests with custom logic", async ({ page }) => {
+  await goTo({ page, path: "/hover_to_prefetch.html" })
+
+  await assertPrefetchedOnHover({ page, selector: "#anchor_with_remote_true" })
+
+  await page.evaluate(() => {
+    document.body.addEventListener("turbo:before-prefetch", (event) => {
+      if (event.target.hasAttribute("data-remote")) {
+        event.preventDefault()
+      }
+    })
+  })
+
+  await assertNotPrefetchedOnHover({ page, selector: "#anchor_with_remote_true" })
+})
+
 test("it doesn't prefetch the page when link has the same location", async ({ page }) => {
   await goTo({ page, path: "/hover_to_prefetch.html" })
   await assertNotPrefetchedOnHover({ page, selector: "#anchor_for_same_location" })