Selection

Redirected from en/nsISelection

Table of contents

  1. 1. Introduction
  2. 2. Glossary
  3. 3. Properties
  4. 4. Methods
  5. 5. See also
  6. 6. External links
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« Gecko DOM Reference

Introduction

Selection is the class of the object returned by window.getSelection() and other methods. It represents the text selection in the greater page, possibly spanning multiple elements, when the user drags over static text and other parts of the page. For information about text selection in an individual text editing element, see Input , TextArea and document.activeElement which typically return the parent object returned from window.getSelection() .

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

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.

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
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.
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.

Properties

anchorNode
Returns the node in which the selection begins.
anchorOffset
Returns the number of characters that the selection's anchor is offset within the anchorNode.
focusNode
Returns the node in which the selection ends.
focusOffset
Returns the number of characters that the selection's focus is offset within the focusNode.
isCollapsed
Returns a Boolean indicating whether the selection's start and end points are at the same position.
rangeCount
Returns the number of ranges in the selection.

Methods

getRangeAt
Returns a range object representing one of the ranges currently selected.
collapse
Collapses the current selection to a single point.
extend
Moves the focus of the selection to a specified point.
modify Requires Gecko 2.0
Changes the current selection.
collapseToStart
Collapses the selection to the start of the first range in the selection.
collapseToEnd
Collapses the selection to the end of the last range in the selection.
selectAllChildren
Adds all the children of the specified node to the selection.
addRange
A range object that will be added to the selection.
removeRange
Removes a range from the selection.
removeAllRanges
Removes all ranges from the selection.
deleteFromDocument
Deletes the selection's content from the document.
selectionLanguageChange
Modifies the cursor Bidi level after a change in keyboard direction.
toString
Returns a string currently being represented by the selection object, i.e. the currently selected text.
containsNode
Indicates if a certain node is part of the selection.

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