<base>: The Document Base URL element

The HTML <base> element specifies the base URL to use for all relative URLs in a document. There can be only one <base> element in a document.

The used base URL of a document can be accessed from scripts with document.baseURI. If the document contains no <base> elements, baseURI defaults to location.href.

Attributes

This element's attributes include the global attributes.

If either of the following attributes are specified, this element must come before other elements with attributes whose values are URLs, such as <link>’s href attribute.

href

The base URL to be used throughout the document for relative URLs. Absolute and relative URLs are allowed.

target

A keyword or author-defined name of the default browsing context to display the result when links or forms cause navigation, for <a> or <form> elements without an explicit target attribute. The attribute value targets a browsing context (such as a tab, window, or <iframe>).

The following keywords have special meanings:

• _self: Load the result into the same browsing context as the current one. (This is the default.)
• _blank: Load the result into a new, unnamed browsing context.
• _parent: Load the result into the parent browsing context of the current one. (If the current page is inside a frame.) If there is no parent, behaves the same way as _self.
• _top: Load the result into the topmost browsing context (that is, the browsing context that is an ancestor of the current one, and has no parent). If there is no parent, behaves the same way as _self.

Usage notes

Multiple <base> elements

If multiple <base> elements are used, only the first href and first target are obeyed — all others are ignored.

In-page anchors

Links pointing to a fragment in the document — e.g. <a href="#some-id"> — are resolved with the <base>, triggering an HTTP request to the base URL with the fragment attached.

For example, given <base href="https://example.com">

...and this link: <a href="#anchor">Anker</a>

...the link points to https://example.com/#anchor.

Open Graph

Open Graph tags do not acknowledge <base>, and should always have full absolute URLs. For example:

<meta property="og:image" content="https://example.com/thumbnail.jpg">

Examples

<base href="https://www.example.com/">
<base target="_blank"> 
<base target="_top" href="https://example.com/">  

Specifications

Browser compatibility