Previously answered questions here said that this was the fastest way:
//nl is a NodeList var arr = Array.prototype.slice.call(nl);
In benc
Assuming nodeList = document.querySelectorAll("div"), this is a concise form of converting nodelist to array.
nodeList = document.querySelectorAll("div")
nodelist
var nodeArray = [].slice.call(nodeList);
See me use it here.