HTML + JS add attribute into a tag?

Use the "setAttribute()" method for Element objects in the DOM

http://www.javascriptkit.com/domref/elementmethods...

However in HTML you should really only create attributes that are recognised as standard (e.g. recommended by W3C) - custom attributes are the domain of XML

Although you could simply add an arbitrary attribute to an HTML document, the browsers won't know what that attribute means, so they won't do anything with it.

However, if what you really want to do is add some sort of marker to a tag so you can do more interesting things with it later, you can add a class or id to it.

For example:

<p id = "output">

This is my paragraph

</p>

is an ordinary paragraph, but because you added the id tag to it, you could do this in the CSS:

p.output {

color: blue;

}

You can also use JavaScript to modify any element that you've added an id to, like this:

<script type = "text/javascript">

p = document.getElementById("p");

p.innerHTML = "The text changed";

</script>

You can also add a class attribute to any element. IDs are unique, but you can apply a class to many elements on the same page, and each element can have more than one class. In this way, you can use css to generate a bunch of different characteristics, and then just apply the classes you want to your HTML elements.

Hope this helps. Stop by the site if you want more examples or to ask another question...