Is there any need to learn JavaScript DOM methods for web development, now we have jQuery et al?

Question

With the availability of JQuery, is there any need to learn direct DOM manipulation with Javascript in order to be a professional web developer/site builder/etc.?

This probably could be asked with Prototype, MooTools, etc. too, but I'm not familiar with them apart from their names.

Answer 1

Note: This question was rephrased so my answer reflects the initial question but I kept on adding.

Absolutely. Jquery IS Javascript and while it does abstract a lot of the cross-browser DOM discrepancies, one is still prone to the same exact parsing errors, scope misunderstandings, and so forth.

Using jQuery without knowing basic DOM knowledge or necessary Javascript knowledge is what I would consider dangerous, somewhat like giving a very powerful gun to a child who just may accidentally shoot himself in the foot without knowledge of how to use such a powerful tool the proper way.

A person that's taught straight with jQuery would have absolutely no idea how to debug issues if the error being thrown refers to anything in the DOM. For something as simple as comparing to see if an element is another element ( for things like current state ), they would try something maybe like:

if ( $('a.current') == $('a.current') ) { }

Which would return false since two unique jQuery objects are created. If they had known how to grab the reference to the DOM nodes they could have just done $('#el')[0] == $('#el')[0].

Anytime you use a jQuery plugin and run into some mysterious behaviour, without DOM knowledge you pretty much have to rely on someone else to help you out. Developers with DOM knowledge would be more able to debug and know the root of the problem, so you're only setting yourself up to lose more time scratching you head puzzled in jQuery land.

Furthermore, if one wishes to ever get to a high knowledge level and not just be an ordinary joe jQuery developer then he would greatly need a vast knowledge of the DOM discrepancies and Javascript in general otherwise you're limiting your skill level by a huge margin.

If you stick around Stackoverflow for awhile you'll see this in day to day questions, in which people who took the easy shortcut lack the basic JS/DOM knowledge necessary to solve their issues.