DocumentFragment - Web APIs 编辑

The DocumentFragment interface represents a minimal document object that has no parent. It is used as a lightweight version of Document that stores a segment of a document structure comprised of nodes just like a standard document. The key difference is due to the fact that the document fragment isn't part of the active document tree structure. Changes made to the fragment don't affect the document (even on reflow) or incur any performance impact when changes are made.

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Constructor

DocumentFragment()

Creates and returns a new DocumentFragment object.

Properties

This interface has no specific properties, but inherits those of its parent, Node, and implements those of the ParentNode interface.

ParentNode.children Read only

Returns a live HTMLCollection containing all objects of type Element that are children of the DocumentFragment object.

ParentNode.firstElementChild Read only

Returns the Element that is the first child of the DocumentFragment object, or null if there is none.

ParentNode.lastElementChild Read only

Returns the Element that is the last child of the DocumentFragment object, or null if there is none.

ParentNode.childElementCount Read only

Returns an unsigned long giving the amount of child elements the DocumentFragment has.

Methods

This interface inherits the methods of its parent, Node, and implements those of the ParentNode interface.

DocumentFragment.querySelector()

Returns the first Element node within the DocumentFragment, in document order, that matches the specified selectors.

DocumentFragment.querySelectorAll()

Returns a NodeList of all the Element nodes within the DocumentFragment that match the specified selectors.

DocumentFragment.getElementById()

Returns the first Element node within the DocumentFragment, in document order, that matches the specified ID. Functionally equivalent to Document.getElementById().

Usage notes

A common use for DocumentFragment is to create one, assemble a DOM subtree within it, then append or insert the fragment into the DOM using Node interface methods such as appendChild() or insertBefore(). Doing this moves the fragment's nodes into the DOM, leaving behind an empty DocumentFragment. Because all of the nodes are inserted into the document at once, only one reflow and render is triggered instead of potentially one for each node inserted if they were inserted separately.

This interface is also of great use with Web components: <template> elements contain a DocumentFragment in their HTMLTemplateElement.content property.

An empty DocumentFragment can be created using the document.createDocumentFragment() method or the constructor.

Example

HTML

<ul id="list"></ul>

JavaScript

var list = document.querySelector('#list')
var fruits = ['Apple', 'Orange', 'Banana', 'Melon']

var fragment = new DocumentFragment()

fruits.forEach(function (fruit) {
  var li = document.createElement('li')
  li.innerHTML = fruit
  fragment.appendChild(li)
})

list.appendChild(fragment)

Result

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• The DOM interfaces index.