<!DOCTYPE html>
<title>Event handlers processing algorithm</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
 <body>
 <div id="foo" style="width: 100px; height: 100px; background-color: black"></div>
 <script>

 // Historically mouseover was special in the spec, but now it is not. See https://github.com/whatwg/html/pull/2398.
 test(function(t) {
     var ev = new Event('mouseover', {cancelable: true});
     document.getElementById("foo").onmouseover = t.step_func(function() { return false });
     document.getElementById("foo").dispatchEvent(ev);
     assert_equals(ev.defaultPrevented, true)
 }, "mouseover listener returning false cancels event (using Event)");

 test(function(t) {
     var ev = new MouseEvent('mouseover', {cancelable: true});
     document.getElementById("foo").onmouseover = t.step_func(function() { return false });
     document.getElementById("foo").dispatchEvent(ev);
     assert_equals(ev.defaultPrevented, true)
 }, "mouseover listener returning false cancels event (using MouseEvent)");

 test(function(t) {
     var ev = new Event('mouseover', {cancelable: true});
     document.getElementById("foo").onmouseover = t.step_func(function() { return true });
     document.getElementById("foo").dispatchEvent(ev);
     assert_equals(ev.defaultPrevented, false)
 }, "mouseover listener returning true doesn't cancel event (using Event)");

 test(function(t) {
     var ev = new MouseEvent('mouseover', {cancelable: true});
     document.getElementById("foo").onmouseover = t.step_func(function() { return true });
     document.getElementById("foo").dispatchEvent(ev);
     assert_equals(ev.defaultPrevented, false)
 }, "mouseover listener returning true doesn't cancel event (using MouseEvent)");

 // beforeunload is tested in html/browsers/browsing-the-web/unloading-documents/beforeunload-canceling.html

 test(function(t) {
     var ev = new Event("click", {cancelable: true});
     document.getElementById("foo").onclick = t.step_func(function() { return false; });
     document.getElementById("foo").dispatchEvent(ev);
     assert_equals(ev.defaultPrevented, true);
 }, "click listener returning false cancels event");

 test(function(t) {
     var ev = new Event("blur", {cancelable: true});
     document.getElementById("foo").onblur = t.step_func(function() { return false; });
     document.getElementById("foo").dispatchEvent(ev);
     assert_equals(ev.defaultPrevented, true);
 }, "blur listener returning false cancels event");

 test(function(t) {
     var ev = new Event("dblclick", {cancelable: true});
     document.getElementById("foo").ondblclick = t.step_func(function() { return false; });
     document.getElementById("foo").dispatchEvent(ev);
     assert_equals(ev.defaultPrevented, true);
 }, "dblclick listener returning false cancels event");
</script>
