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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /html/webappapis/scripting/events/event-handler-processing-algorithm.html - WPT Dashboard Interop Dashboard
<!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>