<!DOCTYPE html>
<meta charset=utf-8>
<title>Printing</title>
<link rel=help href="https://html.spec.whatwg.org/#printing">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
setup({explicit_timeout: true})
</script>
<p>Click on the button below.</p>
<p>If the browser offers to print the current page, dismiss the prompt to
return to this page. The following should then appear in the box marked as
"Output":</p>
<pre>
before calling print()
beforeprint
afterprint
after calling print()
</pre>
<p>If no user dialog appears, either the above or the following should be
printed in the box marked as "Output":</p>
<pre>
before calling print()
after calling print()
</pre>
<p>The test passes if the above criteria are satisfied and "PASS" appears in a
table below this paragraph. The test fails otherwise.</p>
<button onclick="testBtn(this)">Click here!</button>
<h3>Output</h3>
<pre id=output></pre>
<script>
"use strict";
// This test is actually synchronous, but we use async_test()'s nice
// infrastructure around t.step() to capture errors in event listeners. This is
// necessary since it seems like in Chrome, exceptions in beforeprint/afterprint
// event listeners are not propagated to error events. See
// https://crbug.com/977828.
const t = async_test();
const log = [];
function out(str) {
log.push(str);
output.appendChild(document.createTextNode(str + "\n"));
}
function testBtn(btn) {
btn.remove();
window.addEventListener("beforeprint", function (ev) {
// t.step_func() does not preserve `this`, which we test below.
t.step(() => {
out("beforeprint");
assert_equals(Object.getPrototypeOf(ev), Event.prototype);
assert_equals(this, window);
assert_equals(ev.target, window);
assert_equals(ev.type, "beforeprint");
});
});
window.addEventListener("afterprint", function (ev) {
// t.step_func() does not preserve `this`, which we test below.
t.step(() => {
out("afterprint");
assert_equals(Object.getPrototypeOf(ev), Event.prototype);
assert_equals(this, window);
assert_equals(ev.target, window);
assert_equals(ev.type, "afterprint");
});
});
out("before calling print()");
print();
out("after calling print()");
t.step(() => {
try {
assert_array_equals(log, [
"before calling print()",
"beforeprint",
"afterprint",
"after calling print()",
]);
} catch (err) {
try {
assert_array_equals(log, [
"before calling print()",
"after calling print()",
]);
} catch (err) {
assert_unreached("Output does not match either possibility");
}
}
});
t.done();
}
</script>
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