How do I right-click in iOS Safari to access website specific functionality?

More and more desktop websites these days use javascript to offer ***specific website functionality*** which is available when you right-click on something. Often the developers create something that looks like a menu, but could be anything. If I'm browsing desktop websites on iOS Safari (mainly iPad, but sometimes iPhone), how do I perform a right-click to display this functionality? For a simple example, visit https://swisnl.github.io/jQuery-contextMenu/demo.html and try to display the menu under the box which states "right click me". On a desktop it's pretty obvious, but I cannot work out how to trigger it on an iPhone or iPad. I've tried tapping and holding but this either brings up the browser menu or the text selection tool. I've also tried double-tapping but that tends to zoom the page in and out. --- Side note: If you do a Google search for this, you'll find many posts from people assuming that you want to right-click to access functionality that desktop browsers typically offer (such as back, forwards, reload, save as, view page source and inspect element). **This is not the functionality I'm interested in accessing.**