I've read it so many times... "I'd learn JavaScript before learning something like jQuery" - but is this really necessary for every situation? Sure, some people like to know what's going on under the hood, but are there any serious negative side effect of heading straight for jQuery tutorials/books? I want to learn something in my spare time and I've decided on jQuery (or JavaScript if anyone can convince me strongly enough).
The reason of the typical recommendation "learn JS before jQuery" is because you'll find yourself too many times asking yourself how some jQuery snippet works, when it's not a problem of jQuery but JS syntax / etc (e.g. closures).
Go for JS, you won't be disappointed.
A lot of learning and using jQuery comes for free to begin with and can be motivating as it provides an immediate sense of productivity. There does come a point however, where you need to understand JavaScript in order to use jQuery effectively or any other JavaScript framework for that matter. This is particularly pertinent for example, when writing plugins and utility functions.
jQuery is a library, not a language. You've essentially said, "I am thinking of learning how to write English songs. Some people say that you should learn English first, but I'm not convinced that it's worthwhile, I just want to rock."
You can probably still pick up jQuery without learning JavaScript first, but you ultimately will understand nothing of how jQuery is actually working and likely just come to accept that it's magic. Good luck when jQuery breaks or doesn't work how you expected it and can't figure out why your code is broken.
JavaScript is a beautiful language, and worth learning in its own right. Start here: Eloquent Javascript.
That's like asking if it's worth learning learning Objective-C before using Cocoa. It's kind of a weird question, because Cocoa is in Objective-C, much the same way as jQuery is written in JavaScript. When you learn jQuery, you learn some JavaScript whether you like it or not.
I think what you're wondering is more along the lines of "should I learn the underlying JavaScript that jQuery bypasses with its core library and plugins?" It depends on the circumstance, of course; if you need code in a hurry, you're much better off learning jQuery alone. But since your goal seems to be to learn something in your spare time, I personally think it's a good idea to learn basic JavaScript before diving into jQuery:
For the same reason VB6 programmers needed to understand the Windows API to get anything done, and VB.NET and C# programmers need to at least know what MSIL looks like, you should be familiar enough with JavaScript to understand what jQuery is doing. There's a lot of far-out stuff built into JavaScript that most people never need to use, but if you don't know it exists, you'll always overlook good solutions to your problems.
There is no question about it. jQuery is JavaScript. You'll be handicapping yourself severely if you jump straight into jQuery. Your code will be slow and unmaintainable. jQuery is an API, it's not a language.
In fact, you could try jumping into jQuery but I doubt you'll get very far without being frustrated with hurdles that would be otherwise trivial. At the very least, you should understand the concepts in Re-introduction to JavaScript.
JQUERY is just a library, not a substitue for language like JAVASCRIPT. You wont be going ahead in the field of the softare developement by just learning the LIBRARY. Basic understanding of the core langauge is always the better way to go. And of course, once you have that grasp, then you can and should definitley use libary like JQUERY.
It's very good advice actually.
The problem is this. Javascript doesn't work the same way most of the other popular languages work. If you dive into Javascript with the idea that it is similar to Java, C#, Perl, PHP, etc, then you'll end up thinking Javascript is a bizarre, inconsistent mutant language that makes no effing sense whatsoever. This isn't because Javascript makes no sense, it's because Javascript is different at its foundations. Javascript is an object oriented language, but it isn't class based, it's prototype based. The syntax is similar enough to where you could work just fine thinking Javascript was class based up until the point where everything goes horribly wrong.
Learn Javascript first, at least the fundamentals. It's not that difficult, you don't even need a special IDE or compiler since you can just use a browser or WSH. Learning the fundamentals of Javascript will definitely pay off if you're using jQuery.
I feel rather strongly that JavaScript is a more important concept than jQuery or any of it's siblings. These libraries are wonderful, and I can hardly imagine doing anything in the client without their help, but by themselves they only provide some tools and a bit of flashy polish. To actually accomplish any real logic, you will need a good understanding of JavaScript and the objects that are available in the browser.
Short answer to your question is yes if you ever have written anything in any normal language.
If you want to know why, watch JavaScript the good parts by Douglas Crockford (JS guru).