HTML Widgets; Range Slider control; Does not take focus when clicked on a mobile device

On a small mobile device, such as an iPhone or Android phone, clicking on a widget.UI.RangeSlider control did not give it input focus which could be confusing since the previously focused control would retain input focus.

This functionality appears to be by design, at least in Chrome.

Since HTML Widgets are designed to act in a consistent way, focus is now given to a Range Slider when it detects the "touchstart" event. This appears to work on Android device but not iOS at the time of writing.

NOTE: If the Range Slider control had an associated label then, clicking this would, as expected, focus the Range Slider control, on both Android and iOS devices.