What did Substack do to make all links open in new tab?

May I suggest to post this question on a forum better suited to these kind of submissions, like Stack Overflow?

This is probably what you’re looking for: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#...

Knowing Substack, they might have used the JavaScript window.open() method to do that. But adding target="_blank" to a URL (e.g. <a href="https://somesite.net" target="_blank">blah blah blah</a>) also works if you want to go the no-script route

target="_blank"?