LibWeb: Emit "focusin" and "focusout" events

Tests/LibWeb/Text/expected/focus-events.txt

@@ -0,0 +1,6 @@
+   focus target=<INPUT id="a">
+focusin target=<INPUT id="a">
+blur target=<INPUT id="a">
+focusout target=<INPUT id="a">
+focus target=<INPUT id="b">
+focusin target=<INPUT id="b">

Tests/LibWeb/Text/input/focus-events.html

@@ -0,0 +1,54 @@
+<script src="include.js"></script>
+<style>
+    .input {
+        width: 100px;
+        height: 100px;
+        border: 1px solid black;
+    }
+</style>
+<input class="input" id="a" />
+<input class="input" id="b" />
+<script>
+    function elementToString(e) {
+        let element_string = `<${e.nodeName} `;
+        if (e.id) element_string += `id="${e.id}"`;
+        element_string += ">";
+        return element_string;
+    }
+
+    document.addEventListener("focusin", function (e) {
+        const target = elementToString(e.target);
+        println(`focusin target=${target}`);
+    });
+    document.addEventListener("focusout", function (e) {
+        const target = elementToString(e.target);
+        println(`focusout target=${target}`);
+    });
+
+    const a = document.getElementById("a");
+    const b = document.getElementById("b");
+
+    function onFocus(e) {
+        const target = elementToString(e.target);
+        println(`focus target=${target}`);
+    }
+
+    function onBlur(e) {
+        const target = elementToString(e.target);
+        println(`blur target=${target}`);
+    }
+
+    a.addEventListener("focus", onFocus);
+    a.addEventListener("blur", onBlur);
+    b.addEventListener("focus", onFocus);
+    b.addEventListener("blur", onBlur);
+
+    asyncTest(async done => {
+        a.focus();
+        await new Promise(resolve => setTimeout(resolve, 0));
+        b.focus();
+        await new Promise(resolve => setTimeout(resolve, 0));
+
+        done();
+    });
+</script>

Userland/Libraries/LibWeb/DOM/EventHandler.idl

@@ -41,6 +41,8 @@ interface mixin GlobalEventHandlers {
     attribute EventHandler onended;
     attribute OnErrorEventHandler onerror;
     attribute EventHandler onfocus;
+    attribute EventHandler onfocusin;
+    attribute EventHandler onfocusout;
     attribute EventHandler onformdata;
     attribute EventHandler oninput;
     attribute EventHandler oninvalid;

Userland/Libraries/LibWeb/HTML/AttributeNames.h

@@ -141,6 +141,8 @@ namespace AttributeNames {
     __ENUMERATE_HTML_ATTRIBUTE(onended)                    \
     __ENUMERATE_HTML_ATTRIBUTE(onerror)                    \
     __ENUMERATE_HTML_ATTRIBUTE(onfocus)                    \
+    __ENUMERATE_HTML_ATTRIBUTE(onfocusin)                  \
+    __ENUMERATE_HTML_ATTRIBUTE(onfocusout)                 \
     __ENUMERATE_HTML_ATTRIBUTE(onformdata)                 \
     __ENUMERATE_HTML_ATTRIBUTE(onhashchange)               \
     __ENUMERATE_HTML_ATTRIBUTE(oninput)                    \

Userland/Libraries/LibWeb/HTML/EventNames.h

@@ -51,6 +51,8 @@ namespace Web::HTML::EventNames {
     __ENUMERATE_HTML_EVENT(error)                    \
     __ENUMERATE_HTML_EVENT(finish)                   \
     __ENUMERATE_HTML_EVENT(focus)                    \
+    __ENUMERATE_HTML_EVENT(focusin)                  \
+    __ENUMERATE_HTML_EVENT(focusout)                 \
     __ENUMERATE_HTML_EVENT(formdata)                 \
     __ENUMERATE_HTML_EVENT(hashchange)               \
     __ENUMERATE_HTML_EVENT(input)                    \

Userland/Libraries/LibWeb/HTML/Focus.cpp

@@ -79,6 +79,11 @@ static void run_focus_update_steps(Vector<JS::Handle<DOM::Node>> old_chain, Vect
             blur_event->set_related_target(related_blur_target);
             blur_event_target->dispatch_event(blur_event);
         }
+
+        auto focusout_event = UIEvents::FocusEvent::create(blur_event_target->realm(), HTML::EventNames::focusout);
+        focusout_event->set_bubbles(true);
+        focusout_event->set_related_target(related_blur_target);
+        blur_event_target->dispatch_event(focusout_event);
     }
 
     // FIXME: 3. Apply any relevant platform-specific conventions for focusing new focus target.
@@ -123,6 +128,11 @@ static void run_focus_update_steps(Vector<JS::Handle<DOM::Node>> old_chain, Vect
             auto focus_event = UIEvents::FocusEvent::create(focus_event_target->realm(), HTML::EventNames::focus);
             focus_event->set_related_target(related_focus_target);
             focus_event_target->dispatch_event(focus_event);
+
+            auto focusin_event = UIEvents::FocusEvent::create(focus_event_target->realm(), HTML::EventNames::focusin);
+            focusin_event->set_bubbles(true);
+            focusin_event->set_related_target(related_focus_target);
+            focus_event_target->dispatch_event(focusin_event);
         }
     }
 }

Userland/Libraries/LibWeb/HTML/GlobalEventHandlers.h

@@ -34,6 +34,8 @@
     E(onended, HTML::EventNames::ended)                                       \
     E(onerror, HTML::EventNames::error)                                       \
     E(onfocus, HTML::EventNames::focus)                                       \
+    E(onfocusin, HTML::EventNames::focusin)                                   \
+    E(onfocusout, HTML::EventNames::focusout)                                 \
     E(onformdata, HTML::EventNames::formdata)                                 \
     E(oninput, HTML::EventNames::input)                                       \
     E(oninvalid, HTML::EventNames::invalid)                                   \