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SerenityOS
Ladybird: focus events are not fired when focus is moved via keyboard navigation
JavaScript focus events (both focus and blur) do not fire when the focus moves from an element to another via standard keyboard navigation (pressing Tab or Shift+Tab).
For example, if a page with the following HTML contents is open in Ladybird, onfocusHandler2 is not called if I click on the text box and then press Tab to move to the number input.
<!DOCTYPE html>
<html>
<head>
<title>Test page with two inputs</title>
</head>
<body>
<input id="input1" type="text" onblur="onblurHandler1(event)" onfocus="onfocusHandler1(event)">
<input id="input2" type="number" onblur="onblurHandler2(event)" onfocus="onfocusHandler2(event)">
<pre id="con"></pre>
<script>
var con = document.getElementById('con');
function id(elem) { return elem == null ? '(null)' : elem.id; }
function onblurHandler1(event) {
con.innerHTML += `<p>onblurHandler1: target = #${id(event.target)}, relatedTarget = #${id(event.relatedTarget)}</p>`;
}
function onblurHandler2(event) {
con.innerHTML += `<p><b>onblurHandler2: target = #${id(event.target)}, relatedTarget = #${id(event.relatedTarget)}</b></p>`;
}
function onfocusHandler1(event) {
con.innerHTML += `<p>onfocusHandler1: target = #${id(event.target)}, relatedTarget = #${id(event.relatedTarget)}</p>`;
}
function onfocusHandler2(event) {
con.innerHTML += `<p><b>onfocusHandler2: target = #${id(event.target)}, relatedTarget = #${id(event.relatedTarget)}</b></p>`;
}
</script>
</body>
</html>
Although the bug covers focus and blur, I suspect that the focusin and focusout events may be affected too.
Demonstration
At 0:16, I click outside the first input element and the onblurHandler1 function is called. However, if I click again on that element and then press Tab twice, neither onblurHandler1, onblurHandler2 or onfocusHandler2 is called, although the focus moves to and then out of the second input.
https://github.com/SerenityOS/serenity/assets/47182594/f301d75f-4e3d-4a8a-bcb4-0cddb9fcaf8b
