Selection

这是 实验性技术
检查 浏览器兼容性表格 在生产中使用这之前。

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.

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.

特性

Selection.anchorNode 只读
返回 Node in which the selection begins. Can return null if selection never existed in the document (e.g., an iframe that was never clicked on).
Selection.anchorOffset 只读
Returns a number representing the offset of the selection's anchor within the anchorNode 。若 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 只读
返回 Node in which the selection ends. Can return null if selection never existed in the document (for example, in an iframe that was never clicked on).
Selection.focusOffset 只读
Returns a number representing the offset of the selection's anchor within the focusNode 。若 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 只读
Returns a Boolean indicating whether the selection's start and end points are at the same position.
Selection.rangeCount 只读
Returns the number of ranges in the selection.
Selection.type 只读
返回 DOMString describing the type of the current selection.

方法

Selection.addRange()
A Range object that will be added to the selection.
Selection.collapse()
Collapses the current selection to a single point.
Selection.collapseToEnd()
Collapses the selection to the end of the last range in the selection.
Selection.collapseToStart()
Collapses the selection to the start of the first range in the selection.
Selection.containsNode()
Indicates if a certain node is part of the selection.
Selection.deleteFromDocument()
Deletes the selection's content from the document.
Selection.empty()
Removes all ranges from the selection. This is an alias for removeAllRanges() — See Selection.removeAllRanges() 了解更多细节。
Selection.extend()
Moves the focus of the selection to a specified point.
Selection.getRangeAt()
返回 Range object representing one of the ranges currently selected.
Selection.modify()
Changes the current selection.
Selection.removeRange()
Removes a range from the selection.
Selection.removeAllRanges()
Removes all ranges from the selection.
Selection.selectAllChildren()
Adds all the children of the specified node to the selection.
Selection.setBaseAndExtent()
Sets the selection to be a range including all or parts of two specified DOM nodes, and any content located between them.
Selection.setPosition()
Collapses the current selection to a single point. This is an alias for collapse() — See Selection.collapse() 了解更多细节。
Selection.toString()
Returns a string currently being represented by the selection object, i.e. the currently selected text.

注意事项

String representation of a 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 方法。

Multiple ranges in a selection

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 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

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 ).

Behavior of Selection API in terms of editing host focus changes

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:

  1. An editing host gains focus if the previous selection was outside of it.
  2. A Selection API method is called, causing a new selection to be made with the selection range inside the editing host.
  3. Focus then moves to the editing host.

注意 : 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:

词汇表

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
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.
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.

规范

规范 状态 Comment
Selection API
The definition of 'Selection' in that specification.
工作草案 The Selection API specification is based on the HTML Editing APIs specification and focuses on the Selection-related functionality.

浏览器兼容性

更新 GitHub 上的兼容性数据
Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Selection
Chrome 1 Edge 12 Firefox 1
1
GlobalEventHandlers.onselectionchange and GlobalEventHandlers.onselectstart event handlers are supported as of Firefox 52.
IE 9 Opera 9 Safari 1 WebView Android 1 Chrome Android 18 Firefox Android 4
4
GlobalEventHandlers.onselectionchange and GlobalEventHandlers.onselectstart event handlers are supported as of Firefox 52.
Opera Android 10.1 Safari iOS 1 Samsung Internet Android 1.0
addRange
Chrome 1 Edge 12 Firefox Yes IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
anchorNode
Chrome 1 Edge 12 Firefox Yes IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
anchorOffset
Chrome 1 Edge 12 Firefox Yes IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
collapse
Chrome Yes Edge 12 Firefox Yes IE 9 Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
collapseToEnd
Chrome Yes Edge 12 Firefox Yes IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
collapseToStart
Chrome Yes Edge 12 Firefox Yes IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
containsNode
Chrome Yes Edge 12 Firefox 4
4
Before Firefox 35, the method didn't throw if node was null .
IE No Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android 4
4
Before Firefox 35, the method didn't throw if node was null .
Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
deleteFromDocument
Chrome Yes Edge 12 Firefox 55 IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android 55 Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
empty() as alias of removeAllRanges()
Chrome Yes Edge 12 Firefox 55 IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android 55 Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
extend
Chrome Yes Edge 12 Firefox Yes IE No Opera Yes Safari Yes WebView Android No Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
focusNode
Chrome Yes Edge 12 Firefox 3.6 IE 10 Opera Yes Safari 5.1 WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
focusOffset
Chrome Yes Edge 12 Firefox Yes IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
getRangeAt
Chrome Yes Edge 12 Firefox Yes IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
isCollapsed
Chrome 1 Edge 12 Firefox Yes IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
modify
非标
Chrome Yes Edge ≤79 Firefox 4 IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android 4 Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
rangeCount
Chrome Yes Edge 12 Firefox Yes IE Yes Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
removeAllRanges
Chrome Yes Edge 12 Firefox Yes IE Yes Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
removeRange
Chrome 58 Edge 12 Firefox Yes IE ? Opera 45 Safari No WebView Android 58 Chrome Android 58 Firefox Android Yes Opera Android 43 Safari iOS No Samsung Internet Android 7.0
selectAllChildren
Chrome Yes Edge 12 Firefox Yes IE Yes Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
setBaseAndExtent
Chrome Yes Edge 12 Firefox 53 IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android 53 Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
setPosition() as alias of collapse()
Chrome Yes Edge 14 Firefox 55 IE ? Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android 55 Opera Android Yes Safari iOS Yes Samsung Internet Android Yes
toString
Chrome 1 Edge ≤18 Firefox Yes IE ? Opera Yes Safari ? WebView Android Yes Chrome Android Yes Firefox Android Yes Opera Android Yes Safari iOS ? Samsung Internet Android Yes
type
Chrome Yes Edge 12 Firefox 57 IE Yes Opera Yes Safari Yes WebView Android Yes Chrome Android Yes Firefox Android 57 Opera Android Yes Safari iOS Yes Samsung Internet Android Yes

图例

完整支持
完整支持
不支持
不支持
兼容性未知
兼容性未知
实验。期望将来行为有所改变。
实验。期望将来行为有所改变。
非标。预期跨浏览器支持较差。
非标。预期跨浏览器支持较差。
见实现注意事项。

Gecko notes

另请参阅