jQuery .clone()

The .clone() method performs a deep copy of the set of matched elements, meaning that it copies the matched elements as well as all of their descendant elements and text nodes.

When used in conjunction with one of the insertion methods, .clone() is a convenient way to duplicate elements on a page. Consider the following HTML:

<div class="container">
 <div class="hello">Hello</div>
 <div class="goodbye">Goodbye</div>
</div>

As shown in the discussion for .append(), normally when an element is inserted somewhere in the DOM, it is moved from its old location. So, given the code:

$( ".hello" ).appendTo( ".goodbye" );

The resulting DOM structure would be:

<div class="container">
 <div class="goodbye">
 Goodbye
 <div class="hello">Hello</div>
 </div>
</div>

To prevent this and instead create a copy of the element, you could write the following:

$( ".hello" ).clone().appendTo( ".goodbye" );

This would produce:

<div class="container">
 <div class="hello">Hello</div>
 <div class="goodbye">
 Goodbye
 <div class="hello">Hello</div>
 </div>
</div>

Normally, any event handlers bound to the original element are not copied to the clone. The optional withDataAndEvents parameter allows us to change this behavior, and to instead make copies of all of the event handlers as well, bound to the new copy of the element. As of jQuery 1.4, all element data (attached by the .data() method) is also copied to the new copy.

However, objects and arrays within element data are not copied and will continue to be shared between the cloned element and the original element. To deep copy all data, copy each one manually:

// Original element with attached data
var $elem = $( "#elem" ).data( "arr": [ 1 ] ),
 $clone = $elem.clone( true )
 // Deep copy to prevent data sharing
 .data( "arr", $.extend( [], $elem.data( "arr" ) ) );

As of jQuery 1.5, withDataAndEvents can be optionally enhanced with deepWithDataAndEvents to copy the events and data for all children of the cloned element.