Web Design in a Nutshell, 3rd Edition

cloneNode( )

One final method available to you when working with DOM nodes is cloneNode( ). Using this powerful method, you can replicate an individual node (by supplying the method with an argument of false) or the node and all of its descendant nodes (by supplying it with an argument of true). Here is an example of cloneNode( ) in use:

var ul = document.createElement( 'ul' );
var li = document.createElement( 'li' );
li.className = 'check';
for( var i=0; i < 5; i++ ){
  var new_li = li.cloneNode( true );
  new_li.appendChild( document.createTextNode( 'list item ' + ( i + 1 ) ) );
  ul.appendChild( new_li );
}

The benefits may not seem immediately apparent by looking at this example, but there is a major benefit in performance: cloning a node is a much faster process than building a new one from scratch.