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<!doctype html>
<input autofocus onfocus="autofocus_onfocus()"/>
<script>
let autofocused = false;
function autofocus_onfocus() {
autofocused = true;
}
/**
* @param target object: Target to call |focus()| with.
* @param timeout integer | undefined: Timeout to wait for the focus event.
* If unspecified, a timeout will not be set.
* @param focus_target boolean | undefined: Wether to focus the target after
* listening for |onfocus| event.
*/
function wait_focus_event(target, timeout, focus_target) {
return new Promise((resolve) => {
if (timeout)
setTimeout(() => resolve(false), timeout);
target.onfocus = () => resolve(true);
if (focus_target)
target.focus();
});
}
function post_result(destination, result) {
destination.postMessage({focused: result}, "*");
}
window.addEventListener("message", (e) => {
if (e.data.event === "autofocus") {
if (autofocused)
post_result(e.source, true);
wait_focus_event(document.querySelector("input"), e.data.timeout)
.then(result => post_result(e.source, result));
} else if (e.data.event === "focus-window") {
wait_focus_event(window, e.data.timeout, true /* focus_target */)
.then(result => post_result(e.source, result));
} else if (e.data.event === "focus-input") {
const input_element = document.querySelector("input");
wait_focus_event(input_element, e.data.timeout, true /* focus_target */)
.then(result => post_result(e.source, result));
}
});
</script>