HTML5 Custom Data Attribute
HTML5 has a “custom data attribute”. It lets you have any attribute/value
pairs in a tag. Such attribute's name starts with
Here's a example used by Twitter:
<a href="https://twitter.com/share" class="twitter-share-button" data-via="john">Tweet</a>
here's what the html standard say:
A custom data attribute is an attribute in no namespace whose name starts with the string "data-", has at least one character after the hyphen, is XML-compatible, and contains no uppercase ASCII letters.
[2018-10-19 from http://w3c.github.io/html/dom.html#custom-data-attribute]
Why's This Useful?
Here's one example of using it to store accessed date of a site.
<a href="…" data-accessed="2012-09-22">7 Tips You Must Know</a>
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