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<!-- Any copyright is dedicated to the Public Domain.
<!doctype html>
<html>
<head>
<meta charset="utf-8"/>
<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="0" />
<title>Network Monitor test page</title>
<link rel="stylesheet" type="text/css" href="stylesheet_request" />
</head>
<body>
<p>Request cause test</p>
<img src="img_request" />
<img srcset="img_srcset_request" />
<!-- ensure that the two next <img> are offscreen
so that the error listener is registered before we try loading them -->
<div style="height: 2000vh;"></div>
<img loading="lazy" src="lazy_img_request" />
<img loading="lazy" srcset="lazy_img_srcset_request" />
<script type="text/javascript">
"use strict";
function performXhrRequest() {
const xhr = new XMLHttpRequest();
xhr.open("GET", "xhr_request", true);
return new Promise(function performXhrRequestCallback(resolve) {
xhr.onload = resolve;
xhr.send();
});
}
function performFetchRequest() {
return fetch("fetch_request");
}
// Perform some requests with async stacks
function performPromiseFetchRequest() {
return Promise.resolve().then(function performPromiseFetchRequestCallback() {
return fetch("promise_fetch_request");
});
}
function performTimeoutFetchRequest() {
return new Promise(function performTimeoutFetchRequestCallback1(resolve) {
setTimeout(function performTimeoutFetchRequestCallback2() {
resolve(fetch("timeout_fetch_request"));
}, 0);
});
}
function performFavicon() {
return new Promise(function (resolve) {
const link = document.createElement("link");
link.rel = "icon";
link.href = "favicon_request";
document.querySelector("head").appendChild(link);
link.addEventListener("devtools:test:favicon", resolve);
});
}
function performLazyLoadingImage() {
return new Promise(function (resolve) {
const lazyImgs = document.querySelectorAll("img[loading='lazy']");
const promises = [
new Promise(r => lazyImgs[0].addEventListener("error", r)),
new Promise(r => lazyImgs[1].addEventListener("error", r)),
];
// Given that the default display style of <img> is `inline` so
// it's sufficient to scroll to an <img>.
lazyImgs[0].scrollIntoView({ behavior: "instant" });
resolve(Promise.all(promises));
});
}
function performBeaconRequest() {
navigator.sendBeacon("beacon_request");
}
(async function() {
await performXhrRequest();
await performFetchRequest();
await performPromiseFetchRequest();
await performTimeoutFetchRequest();
await performFavicon();
await performLazyLoadingImage();
// Finally, send a beacon request
performBeaconRequest();
})();
</script>
</body>
</html>