feat(core polyfills): Add polyfill for navigation API.

This polyfill adds support for the "navigate" event on the navigation
object. We path "history.pushState" and "history.replaceState" to send
the "navigate" event on the "window.navigation" object when the URL
changes.

This polyfill is for current Firefox and Safari. Chrome based browsers
already support this.

More information on:
https://developer.mozilla.org/en-US/docs/Web/API/Navigation/navigate_event

Author: thet

src/core/polyfills.js

@@ -38,3 +38,44 @@
         true
     );
 })();
+
+// Navigation polyfill for Firefox and Safari, as of 2024-01-04
+// NOTE: this is a very basic polyfill, it only supports firing a `navigate`
+// event on location change and even that without interception support, etc.
+!(function () {
+    if (window.navigation == undefined) {
+
+        class NavigateEvent extends CustomEvent {
+            constructor() {
+                super("navigate");
+                this.destination = { url: undefined };
+            }
+        }
+
+        // Create a navigation object on the window
+        // We create a DOM element for the navigation object so that we can
+        // attach events on it.
+        window.navigation = document.createElement("div");
+
+        const create_event = (args) => {
+            const event = new NavigateEvent();
+            event.destination.url = args[2];
+            return event;
+        };
+
+        // Patch pushState to trigger an `navigate` event on the navigation
+        // object when the URL changes.
+        const pushState = window.history.pushState;
+        window.history.pushState = function () {
+            pushState.apply(window.history, arguments);
+            window.navigation.dispatchEvent(create_event(arguments));
+        };
+
+        // Same with replaceState
+        const replaceState = window.history.replaceState;
+        window.history.replaceState = function () {
+            replaceState.apply(window.history, arguments);
+            window.navigation.dispatchEvent(create_event(arguments));
+        };
+    }
+})();

src/core/polyfills.test.js

@@ -0,0 +1,34 @@
+import "./polyfills";
+
+describe("NavigateEvent tests", () => {
+    afterEach(() => {
+        document.body.innerHTML = "";
+    });
+
+    it("should fire an event when history.pushState is called.", () => {
+        let destination_url;
+
+        window.navigation.addEventListener("navigate", (event) => {
+            destination_url = event.destination.url;
+        });
+
+        const path = "foo/bar/baz.html";
+        history.pushState(null, "", path);
+
+        expect(destination_url).toBe(path);
+    });
+
+
+    it("should fire an event when history.replaceState is called.", () => {
+        let destination_url;
+
+        window.navigation.addEventListener("navigate", (event) => {
+            destination_url = event.destination.url;
+        });
+
+        const path = "foo/bar/baz.html";
+        history.replaceState(null, "", path);
+
+        expect(destination_url).toBe(path);
+    });
+});