Calculated field for external URL

We have an app, where each item contains a field for a website URL and a calculated field. The calculated field needs to open that external URL 'silently, in the background' and then read through the HTML to see if a particular link exists.

For example, for an item where the website URL is https://podio.com/site/partners, the calculated field needs to evaluate if the page includes one or more links to globiflow.com. With an IF/ELSE, the calculated field would ultimately display text like: "One or More Links Exist!"

Can anyone help with the javascript to accomplish this? Thank you!