Anyone know how to define classes with attributes via Pug?

If you're a programmer that's dealt with Node and JavaScript, you should know what the hell I'm mentioning. I think after watching some tutorial videos, I kind of get how to define classes and create attributes, but how do I code it so specific attributes are linked to the specific classes? I'm also unsure which pug files to write this code in. I've already created a new Express app with Pug templates in Visual Studio, so do take that assumption in consideration.
Anyone know how to define classes with attributes via Pug?
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