I am just asking :P I want to make websites and stuff.

It really depends on what you find more comfortable for yourself and what you're trying to do. p5.dom has a basic set of DOM methods to create and manipulate HTML elements. jQuery has a much more extensive set of features. If you are doing a primarily HTML based project and need to do a lot of intensive DOM manipulation, I would recommend jQuery. If you are just trying to add in some DOM integration to a canvas-based sketch, p5.dom might make more sense.
For future reference, the forum is a great place for questions like these and longer discussions.
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It really depends on what you find more comfortable for yourself and what you're trying to do. p5.dom has a basic set of DOM methods to create and manipulate HTML elements. jQuery has a much more extensive set of features. If you are doing a primarily HTML based project and need to do a lot of intensive DOM manipulation, I would recommend jQuery. If you are just trying to add in some DOM integration to a canvas-based sketch, p5.dom might make more sense.
For future reference, the forum is a great place for questions like these and longer discussions.