This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.

A Selection object represents the range of text selected by the user or the current position of the caret. To obtain a Selection object for examination of modification, call window.getSelection().
 

Properties

Selection.anchorNode
Returns the Node in which the selection begins.
Selection.anchorOffset
Returns a number representing the offset of the selection's anchor within the anchorNode. If anchorNode is a text node, this is the number of characters within anchorNode preceding the anchor. If anchorNode is an element, this is the number of child nodes of the anchorNode preceding the anchor.
Selection.focusNode
Returns the Node in which the selection ends.
Selection.focusOffset
Returns a number representing the offset of the selection's anchor within the focusNode. If focusNode is a text node, this is the number of characters within focusNode preceding the focus. If focusNode is an element, this is the number of child nodes of the focusNode preceding the focus.
Selection.isCollapsed
Returns a Boolean indicating whether the selection's start and end points are at the same position.
Selection.rangeCount
Returns the number of ranges in the selection.

Methods

Selection.getRangeAt()
Returns a Range object representing one of the ranges currently selected.
Selection.collapse()
Collapses the current selection to a single point.
Selection.extend()
Moves the focus of the selection to a specified point.
Selection.modify()
Changes the current selection.
Selection.collapseToStart()
Collapses the selection to the start of the first range in the selection.
Selection.collapseToEnd()
Collapses the selection to the end of the last range in the selection.
Selection.selectAllChildren()
Adds all the children of the specified node to the selection.
Selection.addRange()
A Range object that will be added to the selection.
Selection.removeRange()
Removes a range from the selection.
Selection.removeAllRanges()
Removes all ranges from the selection.
Selection.deleteFromDocument()
Deletes the selection's content from the document.
Selection.toString()
Returns a string currently being represented by the selection object, i.e. the currently selected text.
Selection.containsNode()
Indicates if a certain node is part of the selection.

Notes

String representation of a selection

Calling the Selection.toString() method returns the text contained in the selection, e.g.:

var selObj = window.getSelection();
window.alert(selObj); 

Note that using a selection object as the argument to window.alert will call the object's toString method.

Multiple ranges in a selection

A selection object represents the ranges that the user has selected. Typically, it holds only one range, accessed as follows:

var selObj = window.getSelection();
var range  = selObj.getRangeAt(0);
  • selObj is a Selection object
  • range is a Range object

As the Selection API specification notes, the Selection API was initially created by Netscape and used multiple ranges, for instance, to allow the user to select a column from a <table>. However browsers other than Gecko did not implement multiple ranges, and the specification also requires the selection to always have a single range.

Selection and input focus

Selection and input focus (indicated by Document.activeElement) have a complex relation, that depends on the browser. In cross-browser compatible code it's better to handle them separately.

Safari and Chrome (unlike Firefox) historically focus the element containing selection when modifying the selection programmatically, but this might change in the future (see W3C bug 14383 and WebKit bug 38696).

Glossary

Other key terms used in this section.

anchor
The anchor of a selection is the beginning point of the selection. When making a selection with a mouse, the anchor is where in the document the mouse button is initially pressed. As the user changes the selection using the mouse or the keyboard, the anchor does not move.
focus of a selection
The focus of a selection is the end point of the selection. When making a selection with a mouse, the focus is where in the document the mouse button is released. As the user changes the selection using the mouse or the keyboard, the focus is the end of the selection that moves. Note: This is not the same as the focused element of the document, as returned by document.activeElement.
range
A range is a contiguous part of a document. A range can contain entire nodes as well as portions of nodes, such as a portion of a text node. A user will normally only select a single range at a time, but it's possible for a user to select multiple ranges (e.g. by using the Control key). A range can be retrieved from a selection as a range object. Range objects can also be created via the DOM and programmatically added or removed from a selection.

Specifications

Specification Status Comment
HTML Editing APIs
The definition of 'Selection' in that specification.
Editor's Draft Initial (older) definition
Selection API
The definition of 'Selection' in that specification.
Working Draft The Selection API specification is based on the HTML Editing APIs specification and focuses on the Selection-related functionality.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support (Yes) (Yes) 9 (Yes) (Yes)
modify() ? 4.0 (2) ? ? ?
Feature Android Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support ? (Yes) ? ? ? ?
modify() ? 4.0 (2) 1.0 ? ? ?

See also

Gecko notes