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 or manipulation, call window.getSelection()
.
A user may make a selection from left to right (in document order) or right to left (reverse of document order). The anchor is where the user began the selection and the focus is where the user ends the selection. If you make a selection with a desktop mouse, the anchor is placed where you pressed the mouse button, and the focus is placed where you released the mouse button.
Note: Anchor and focus should not be confused with the start and end positions of a selection. The anchor can be placed before the focus or vice-versa, depending on the direction you made your selection.
Calling the Selection.toString()
method returns the text contained within 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.
A selection object represents the Range
s 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 allowed 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 (indicated by Document.activeElement
) have a complex relationship that varies by browser. In cross-browser compatible code, it's better to handle them separately.
Safari and Chrome (unlike Firefox) currently focus the element containing selection when modifying the selection programmatically; it's possible that this may change in the future (see W3C bug 14383 and WebKit bug 38696).
The Selection API has a common behavior (i.e., shared between browsers) that governs how focus behavior changes for editing hosts after certain methods are called.
The behavior is as follows:
- An editing host gains focus if the previous selection was outside of it.
- A Selection API method is called, causing a new selection to be made with the selection range inside the editing host.
- Focus then moves to the editing host.
Note: The Selection API methods may only move focus to an editing host, not to other focusable elements (e.g., <a>
).
The above behavior applies to selections made using the following methods:
And when the Range
is modified using the following methods:
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.
-
editing host
-
An editable element (e.g., an HTML element with contenteditable
set, or the HTML child of a document that has designMode
enabled).
-
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.
-
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.