You can download the html with fetch and then parse it with DomParser API.
fetch('somePage.html')
.then(function(response) {
// When the page is loaded convert it to text
return response.text()
})
.then(function(html) {
// Initialize the DOM parser
var parser = new DOMParser();
// Parse the text
var doc = parser.parseFromString(html, "text/html");
// You can now even select part of that html as you would in the regular DOM
// Example:
// var docArticle = doc.querySelector('article').innerHTML;
console.log(doc);
})
.catch(function(err) {
console.log('Failed to fetch page: ', err);
});