docs: function( url, cb ) {
  		var xhr = new window.XMLHttpRequest();
  		if ( "withCredentials" in xhr ) {
  			xhr.open( "GET", url, true );
  		} else if ( typeof window.XDomainRequest !== "undefined" ) { //IE
  			xhr = new window.XDomainRequest();
  			xhr.open( "GET", url );
  		}
  		if( cb ){
  			xhr.onload = cb;
  		}
  		xhr.send();
  		return xhr;
  	}