Override preventDefault() of touch/gestures in iOS Content Blocker

• Component: JavaScriptCore
• Status: NEW ---

[Dean Murphy]

Some websites are using preventDefault() on touch/gesture evens within javascript to prevent the callout menu.

For example: If you visit news.google.com on an iPhone, you are unable to long-tap the hyperlinks to copy link/open in new tab/add to reading list. The only workaround I can find for this particular website is to refresh into a desktop view.

The particular script that handles these events can be blocked via content blocker, however blocking the whole script affects the page loading correctly as overriding touch handlers are a small part of what the script as a whole does. 

Maybe have an option within the blockerList.json to ignore 'preventDefault()' of touch/gesture overrides?

[Benjamin Poulain]

This one is very tricky.

There are many valid use cases for calling preventDefault() on touch events. I suspect we would mostly break content if rules start ignore it.

A problem is that we do not provide a way for the page to only cancel certain native gestures. It is quite possible the long press is only cancelled as a by-product of another gesture handling.

I'll import this too to keep track of this particular problem, but IMHO extending the platform should have the priority.

[Radar WebKit Bug Importer]

<rdar://problem/21798014>