data-* (attribute)

The data-* global attributes form a class of attributes called custom data attributes, that allow proprietary information to be exchanged between the HTML and its DOM representation by scripts. All such custom data are available via the HTMLElement interface of the element the attribute is set on. The HTMLElement.dataset property gives access to them.
The * may be replaced by any name following the production rule of xml names with the following restrictions:

• the name must not start with xml, whatever case is used for these letters;
• the name must not contain any semicolon (U+003A);
• the name must not contain capital A to Z letters.

Note that the HTMLElement.dataset property is a DOMStringMap, and the name of the custom data attribute data-test-value will be accessible via HTMLElement.dataset.testValue ( or HTMLElement.dataset["testValue"] ) as any dash (U+002D) is replaced by the capitalization of the next letter, converting the name to camelcase.

Usage

By adding data-* attributes, even ordinary HTML elements can become rather complex and powerful program-objects. For example, a space-ship "sprite" in a game could be a simple <img> element with a class attribute and several data-* attributes:

<img class="spaceship cruiserX3" src="shipX3.png"
  data-ship-id="324"   data-weapons="laserI laserII"   data-shields="72%"
  data-x="414354" data-y="85160" data-z="31940"
  onclick="spaceships[this.dataset.shipId].blasted()"
</img>

(See more here)

Specifications

Specification	Status	Comment
WHATWG HTML Living Standard The definition of 'data-*' in that specification.	Living Standard	No change from latest snapshot, HTML5.1
HTML5.1 The definition of 'data-*' in that specification.	Recommendation	Snapshot of WHATWG HTML Living Standard, no change from HTML5
HTML5 The definition of 'data-*' in that specification.	Recommendation	Snapshot of WHATWG HTML Living Standard, initial definition.

Browser compatibility

See also

• All global attributes.
• The HTMLElement.dataset property that allows to access and modify these values.