In my opinion, having read parts of jQuery's source code on various occasions… You should only read it for entertainment value, it makes for fascinating brain t

In my opinion, having read parts of jQuery's source code on various occasions… You should only read it for entertainment value, it makes for fascinating brain teasers. Here's one snippet I had the opportunity to read recently: contains = hasCompare || rnative.test( docElem.contains ) ? function( a, b ) { var adown = a.nodeType === 9 ? a.documentElement : a, bup = b && b.parentNode; return a === bup || !!( bup && bup.nodeType === 1 && ( adown.contains ? adown.contains( bup ) : a.compareDocumentPosition && a.compareDocumentPosition( bup ) & 16 )); } : function( a, b ) { if ( b ) { while ( (b = b.parentNode) ) { if ( b === a ) { return true; } } } return false; };