fetch("https://vk.com/foaf.php?id=1", {mode: 'no-cors'})
.then(res => res.text())
.then(str => new DOMParser().parseFromString(str, "text/xml"))
.then(data => console.log(data))
В ответе:
<html xmlns="http://www.w3.org/1999/xhtml"><parsererror style="display: block; white-space: pre; border: 2px solid #c77; padding: 0 1em 0 1em; margin: 1em; background-color: #fdd; color: black"><h3>This page contains the following errors:</h3><div style="font-family:monospace;font-size:12px">error on line 1 at column 1: Extra content at the end of the document
</div><h3>Below is a rendering of the page up to the first error.</h3></parsererror><body></body></html>
Если использовать метод cors, то вообще выдаст ошибку.
Простой
