JavaScript: The Definitive Guide

2017-07-07 02:10:07

25.195. Link: a hyperlink or anchor in an HTML document

DOM Level 0: Node Element HTMLElement Link

25.195.1. Properties

The most important property of a Link is its href, which is the URL to which it links. The Link object also defines a number of other properties that hold portions of the URL. For each of these properties, the example given is a portion of the following (fictitious) URL:

http://www.oreilly.com:1234/catalog/search.html?q=JavaScript&m=10#results

String hash: Specifies the anchor portion of the Link's URL, including the leading hash (#) markfor example, "#results". This anchor portion of a URL refers to a named position within the document referenced by the Link. In HTML files, positions are named with the name attribute of the <a> tag. (see Anchor).
String host: Specifies the hostname and port portions of a Link's URLfor example, "www.oreilly.com:1234".
String hostname: Specifies the hostname portion of a Link's URLfor example, "www.oreilly.com".
String href: Specifies the complete text of the Link's URL, unlike other Link URL properties that specify only portions of the URL.
String pathname: Specifies the pathname portion of a Link's URLfor example, "/catalog/search.html".
String port: Specifies the port portion of a Link's URLfor example, "1234".
String protocol: Specifies the protocol portion of a Link's URL, including the trailing colonfor example, "http:".
String search: Specifies the query portion of a Link's URL, including the leading question markfor example, "?q=JavaScript&m=10".

In addition to these URL-related properties, Link objects also define properties that correspond to the attributes for the HTML <a> and <area> tags:

Property	Attribute	Description
`String accessKey`	`accesskey`	Keyboard shortcut
`String charset`	`charset`	Encoding of the destination document
`String coords`	`coords`	For `<area>` tags
`String hreflang`	`hreflang`	Language of the linked document
`String name`	`name`	Anchor name; see `Anchor`
`String rel`	`rel`	Link type
`String rev`	`rev`	Reverse link type
`String shape`	`shape`	For `<area>` tags
`long tabIndex`	`tabindex`	Link's position in tabbing order
`String target`	`target`	Name of the frame or window in which the destination document is to be displayed
`String type`	`type`	Content type of the destination document

25.195.2. Methods

blur( ): Takes keyboard focus away from the link.
focus( ): Scrolls the document so the link is visible and gives keyboard focus to the link.

25.195.3. Event Handlers

The Link object has special behavior for three event handlers:

onclick: Invoked when the user clicks on the link.
onmouseout: Invoked when the user moves the mouse off the link.
onmouseover: Invoked when the user moves the mouse over the link.

25.195.4. HTML Syntax

A Link object is created with standard <a> and </a> tags. The href attribute is required for all Link objects. If the name attribute is also specified, an Anchor object is also created:

<a href="url" // The destination of the link [ name="anchor_tag" ] // Creates an Anchor object [ target="window_name" ] // Where the new document should be displayed [ onclick="handler" ] // Invoked when link is clicked [ onmouseover="handler" ] // Invoked when mouse is over link [ onmouseout="handler" ] // Invoked when mouse leaves link >link text or image // The visible part of the link </a>

25.195.5. Description

A Link object represents a hyperlink in a document. Links are usually created with <a> tags that have an href attribute defined, but they may also be created with <area> tags inside a client-side image map. When an <a> tag has a name attribute instead of an href attribute, it defines a named position in a document and is represented by an Anchor object instead of a Link object. See Anchor for details.

All links in a document (whether created with <a> or <area> tags) are represented by Link objects in the links[] array of the Document object.

The destination of a hypertext link is a URL, of course, and many of the properties of the Link object specify the contents of that URL. In this way, the Link object is similar to the Location object, which also has a full set of URL properties.

25.195.6. Example

// Get the URL of the first hyperlink in the document var url = document.links[0].href;

25.195.7. See Also

Anchor, Location