HTML <bdi> Tag
The HTML <bdi> tag is used to create the 'bdi' element. This element is used on a span of text that needs to be isolated from its surroundings for the purposes of bidirectional text formatting.
This is useful when the text-direction is unknown, such as displaying user content where the directionality could change depending on the user. For example, a website with left-to-right text may display a list of usernames. Some users might have a username that runs right-to-left (such as Arabic, Hebrew, Persian, Thaana, Urdu, etc). In this case, the <bdi> element allows you to honor the correct directionality of the username.
While it's true that you can use the <bdo> tag to explicitly set the text direction, that tag is no good when the text direction is unknown (such is the case with user generated content). This is where the <bdi> comes in handy, as you can isolate the text with the unknown text direction from its surrounding text.
Syntax
The <bdi> tag is written as <bdi></bdi> with the text with the unknown directionality inserted between the start and end tags.
Like this:
Example
Here is a list of usernames from an online forum website. Note that each username is marked up with the <bdi> tag.
Below is an example of what would happen if we didn't use the <bdi> tag. Notice that the position of the third username (إيان) and the number of posts has been switched around. The number of posts is now to the left of the username. This is because the browser thinks that the post count is part of the Arabic text. To overcome this, we can use the <bdi> tag as we did above.
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 <bdi> element accepts the following attributes.
Element-Specific Attributes
This table shows the attributes that are specific to the <bdi> tag/element.
| Attribute | Description |
|---|---|
| none* |
* Note that the global dir attribute defaults to auto on this element (it never inherits from the parent element like with other elements).
Global Attributes
The following attributes are standard across all HTML5 elements. Therefore, you can use these attributes with the <bdi> 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 <bdi> 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 <bdi> element is new in HTML5.
To see more details on the element, see HTML5 <bdi> Tag. Also check out the links to the official specifications below.
Template
Here's a template for the <bdi> 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.
Note that the <bdi> element does not actually have any local attributes (i.e. attributes that are specific to the element), but the following global attributes and event handlers are available to the element (and all other HTML elements).
For more information on attributes for this tag, see HTML5 <bdi> Tag.
* The dir global attribute defaults to auto on this element (it never inherits from the parent element like with other elements).
Tag Details
For more details about the <bdi> tag, see HTML5 <bdi> Tag.
Specifications
Here are the official specifications for the <bdi> element.
- HTML5 Specification (W3C)
- HTML Living Standard (WHATWG)
- Current W3C Draft (the next version that is currently being worked on)
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.