Question

-webkit-overflow-scrolling is new to iOS 5. I’m looking for a CSS polyfill or a method rather than user agent reading for detecting if this feature is available. Modernizer don’t detect this.

Answer 1

Modernizr doesn’t detect the property by default, but you can add your own test to it.

Just call this code anywhere:

Modernizr.addTest('overflowscrolling', function() {
    return Modernizr.testAllProps("overflowScrolling");
});

after the call, your body element will either have a overflowscrolling or a no-overflowscrolling class and you can check the support against Modernizr.overflowscrolling.