いろいろなものを配列に変換する

HTMLElement.prototype.to_a=function()Array.slice(this);

Element.prototype.to_a=function()Array.slice(this);

HTMLCollection.prototype.to_a=function()Array.slice(this);

XPathResult.prototype.to_a=function(){
var r=[];
switch(this.resultType){
 case XPathResult.ORDERED_NODE_SNAPSHOT_TYPE:
 case XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE:
  for(var i=0;i<this.snapshotLength;i++)r.push(this.snapshotItem(i));
  break;
 case XPathResult.ORDERED_NODE_ITERATOR_TYPE:
 case XPathResult.UNORDERED_NODE_ITERATOR_TYPE:
  var i;
  while(i=this.iterateNext())r.push(i);
  break;
 case XPathResult.STRING_TYPE:
  r.push(this.stringValue);
  break;
 case XPathResult.NUMBER_TYPE:
  r.push(this.numberValue);
  break;
 case XPathResult.BOOLEAN_TYPE:
  r.push(this.booleanValue);
  break;
 case XPathResult.FIRST_ORDERED_NODE_TYPE:
 case XPathResult.ANY_UNORDERED_NODE_TYPE:
  r.push(this.singleNodeValue);
  break;
}
return r;
}

document.evaluate('//a',document,null,0,null).to_a()のように使う。