The length read-only property of the CSSValueList interface represents the number of CSSValues in the list. The range of valid values of the indices is 0 to length-1 inclusive.
The read-only DataTransferItemList.length property returns the number of items in the list. If the list has no items, or is disabled (because it has no data store at all), this property returns zero.
The length read-only property of the SourceBufferList interface returns the number of SourceBuffer objects in the list.
The length read-only property of the TrackDefaultList interface returns the number of TrackDefault objects in the list.