Is it OK to add your own attributes to HTML elements? [duplicate]

Question

Possible Duplicates:
Custom attributes - Yay or nay?
Non-Standard Attributes on HTML Tags. Good Thing? Bad Thing? Your Thoughts?

In current learning project I am working on, I need to add an attribute whose value will be a number. At first I thought of using "id" for this purpose but an answer revealed that it is not good to do that.

Is it OK if I create my own attribute, say "messid" and assign a numeric value such as "12", "6" etc to it?

Here is why I want to do this so that you can correct me if I am doing it totally wrong: I need to access this number in my JavaScript (using jQuery). Just taking the value of attribute is easy but extracting the numeric value from a string like "m12" or "m6" is a pain. (I am a beginner in JavaScript world.)

Answer 1

There has been much discussion about this:

• Custom attributes - Yay or nay?
• How to store arbitrary data for some HTML tags
• Non-Standard Attributes on HTML Tags. Good Thing? Bad Thing? Your Thoughts?

At the end of the day, I am on the camp that believes data attributes are the best way to go. They are being introducted in HTML5 to avoid name conflicts. Essentially, if you want to store anything data related you just prepend "data-" on the attribute name:

<div class="user" data-userid="5"></div> 

The only con to the whole thing is then that your XHTML won't validate, but I honestly don't care about that stuff. (That's right, I said it)