Can I add a custom attribute to an HTML tag?

Question

Can I add a custom attribute to an HTML tag like the following?

Answer 1

Yes, you can do it!

Having the next HTML tag:

We can access their attributes with JavaScript:

element.getAttribute('key'); // Getter
element.setAttribute('key', 'value'); // Setter

Element.setAttribute() put the attribute in the HTML tag if not exist. So, you dont need to declare it in the HTML code if you are going to set it with JavaScript.

key: could be any name you desire for the attribute, while is not already used for the current tag. value: it's always a string containing what you need.