Javascript [Electronic resources] : The Definitive Guide (4th Edition) نسخه متنی

Availability

DOM Level 1 Core

Synopsis

Node insertBefore(Node newChild,
Node refChild)
throws DOMException;

Arguments

newChild

The node to be inserted into the tree. If it is a DocumentFragment,
its children are inserted instead.

refChild

The child of this node before which
newChild is to be inserted. If this
argument is null,
newChild is inserted as the last child of
this node.

Returns

The node that was inserted.

Throws

This method may throw a DOMException with the following
code values:

HIERARCHY_REQUEST_ERR

This node does not support children, or it does not allow children of
the specified type, or newChild is an
ancestor of this node (or is this node itself ).

WRONG_DOCUMENT_ERR

The ownerDocument property of
newChild and this node are different.

NO_MODIFICATION_ALLOWED_ERR

This node is read-only and does not allow insertions or the parent of
newChild is read-only and does not allow
deletions.

NOT_FOUND_ERR

refChild is not a child of this node.

Description

This method inserts the node newChild into
the document tree as a child of this node. The new node is positioned
within this node's childNodes[] array so
that it comes immediately before the
refChild node. If
refChild is null,
newChild is inserted at the end of
childNodes[], just as with the
appendChild( ) method. Note that it is illegal to
call this method with a refChild that is
not a child of this node.

If newChild is already in the document
tree, it is removed from the tree and then reinserted at its new
position. If newChild is a
DocumentFragment node, it is not inserted itself; instead, each of
its children is inserted, in order, at the specified location.

Example

The following function inserts a new paragraph at the beginning of a
document:

function insertMessage(message) {
var paragraph = document.createElement("p");
  // Create a <p> Element
var text = document.createTextNode(message);
  // Create a Text node
paragraph.appendChild(text);
                  // Add text to the paragraph
// Now insert the paragraph before the first child of the body
document.body.insertBefore(paragraph, document.body.firstChild)
}

See Also

Node.appendChild( ), Node.removeChild( ), Node.replaceChild( )