What are “data-url” and “data-key” attributes of tag?

Question

I\'ve faced two strange attributes of an html tag . They are \"data-url\" and \"data-key\".

What are they and how

Answer 1

A new feature being introduced in HTML 5 is the addition of custom data attributes. Simply, the specification for custom data attributes states that any attribute that starts with “data-” will be treated as a storage area for private data (private in the sense that the end user can’t see it – it doesn’t affect layout or presentation). This allows you to write valid HTML markup (passing an HTML 5 validator) while, simultaneously, embedding data within your page. A quick example: