HTML <base> Tag
The HTML <base> tag is used to create a 'base' element. This enables web authors to create a base URL for the purpose of resolving relative URLs.
For example, you can set the base URL once at the top of your page, then all relative links on the page will use that URL as if it was the current page.
Syntax
The <base> tag is written as <base href="" target=""> (no end tag). The <base> must have either an href attribute, a target attribute, or both.
Like this:
The <base> tag must be inserted between the document's <head> tags, and there must be no more than one <base> element per document.
Like this:
Example
The above link will actually resolve to http://www.html.am/html-editors/online-html-editor.cfm regardless of the URL of the current page. This is because the base URL (http://www.html.am/) will be prepended to the (relative) URL indicated in the link (html-editors/online-html-editor.cfm).
Modify the code and click Run to change the value of the <base> element.
Attributes
Attributes can be added to an HTML element to provide more information about how the element should appear or behave.
There are 3 kinds of attributes that you can add to your HTML tags: Element-specific, global, and event handler content attributes.
The <base> element accepts the following attributes.
Element-Specific Attributes
This table shows the attributes that are specific to the <base> tag/element.
| Attribute | Description |
|---|---|
| href | Specifies the URI/URL to use. |
| target | Target frame/window |
Global Attributes
The following attributes are standard across all HTML5 elements. Therefore, you can use these attributes with the <base> tag , as well as with all other HTML tags.
- accesskey
- class
- contenteditable
- contextmenu
- dir
- draggable
- dropzone
- hidden
- id
- inert
- itemid
- itemprop
- itemref
- itemscope
- itemtype
- lang
- spellcheck
- style
- tabindex
- title
- translate
For a full explanation of these attributes, see HTML 5 global attributes.
Event Handler Content Attributes
Event handler content attributes enable you to invoke a script from within your HTML. The script is invoked when a certain "event" occurs. Each event handler content attribute deals with a different event.
Below are the standard HTML5 event handler content attributes.
Again, you can use any of these with the <base> element, as well as any other HTML5 element.
- onabort
- oncancel
- onblur
- oncanplay
- oncanplaythrough
- onchange
- onclick
- oncontextmenu
- ondblclick
- ondrag
- ondragend
- ondragenter
- ondragexit
- ondragleave
- ondragover
- ondragstart
- ondrop
- ondurationchange
- onemptied
- onended
- onerror
- onfocus
- onformchange
- onforminput
- oninput
- oninvalid
- onkeydown
- onkeypress
- onkeyup
- onload
- onloadeddata
- onloadedmetadata
- onloadstart
- onmousedown
- onmousemove
- onmouseout
- onmouseover
- onmouseup
- onmousewheel
- onpause
- onplay
- onplaying
- onprogress
- onratechange
- onreadystatechange
- onscroll
- onseeked
- onseeking
- onselect
- onshow
- onstalled
- onsubmit
- onsuspend
- ontimeupdate
- onvolumechange
- onwaiting
For a full explanation of these attributes, see HTML 5 event handler content attributes.
Differences Between HTML 4 & HTML 5
The target attribute was added in HTML5.
To see more detail on the two versions see HTML5 <base> Tag and HTML4 <base> Tag. Also check out the links to the official specifications below.
Template
Here's a template for the <base> tag with all available attributes for the tag (based on HTML5). These are grouped into attribute types, each type separated by a space. In many cases, you will probably only need one or two (if any) attributes. Simply remove the attributes you don't need.
For more information on attributes for this tag, see HTML5 <base> Tag and HTML4 <base> Tag.
Tag Details
For more details about the <base> tag, see HTML5 <base> Tag and HTML4 <base> Tag.
Specifications
Here are the official specifications for the <base> element.
- HTML5 Specification (W3C)
- HTML Living Standard (WHATWG)
- Current W3C Draft (the next version that is currently being worked on)
- HTML 4 (W3C)
What's the Difference?
W3C creates "snapshot" specifications that don't change once defined. So the HTML5 specification won't change once it becomes an official recommendation. WHATWG on the other hand, develops a "living standard" that is updated on a regular basis. In general, you will probably find that the HTML living standard will be more closely aligned to the current W3C draft than to the HTML5 specification.