As bdt101 mentioned here[1], the way they're using Array.prototype.slice.call is...

		tg3 on March 23, 2013 \| parent \| context \| favorite \| on: Show HN: Heap is a new approach to analytics. Just... As bdt101 mentioned here[1], the way they're using Array.prototype.slice.call is supported by IE8. It is not supported when trying to slice a NodeList, as a NodeList is not a JScript object. 1 - https://news.ycombinator.com/item?id=5424874