I code CSS/XHTML like it should be my mother language, and I do write valid, semantic code following guidelines of accessibility and such.
But I want to learn Unobtrusive JavaScripting, but with a total non-programmer brain I need some motivation / tips / etc., like what's the best way to learn it, and how long does it take/did it take you before you could feel the power of knowledge? :)
PS: I do have an understanding on how JavaScript works and changes the DOM etc.. I think it's more about learning the syntax by head instead of having to look it up.
See also:
Suggestions for someone starting javascript programming.
Just use it. Really, the more time you spend reading and writing the language, the more natural it becomes. Use Firebug or an equivalent console to test short ideas; take an existing web page and wire up events interactively from the command line, get used to the idea of writing behavioral code as a separate process from writing markup.
If you want a good book, i can recommend the excellent jQuery in Action - yes, it's targeted at jQuery users, but the concepts apply regardless of your choice in libraries.
Motivation, sorry can't help there.
Syntax is learned by rote. The rules are simple, and reasonably consistent, so in truth syntax isn't that hard.
What you conflate with syntax are likely the other aspects like what properties are available on what objects, what functions to call, what does your framework provide. That, again, is basically rote memorization.
Many frameworks add a little bit of syntax through clever use of the JavaScript syntax, and you'll need to learn those as well.
But when it all comes down to it, the only way to learn this stuff is to use it.
You can't read about it, you have to do it.
Find an issue that you want to work on, a feature for your site or whatever, and attack that.
If you find a tutorial or whatever on line that does what you want, TYPE IN THE CODE, don't cut and paste it. As you type it in, question every symbol or character, try to understand why you're typing what you are typing.
Make an effort to change things, even if it's just variable names, because then you get a better idea of what things are being used for, and how they're referenced. It also lets you focus on a small part of the larger program.
If you're changing the "window1" variable to "myWindow", then at least you can look at the code as "blah blah blah window1 blah blah window1" without having to understand all of it.
Start small, don't worry about "doing it right", etc. so much as just being successful. If the way it's done doesn't bother you, then you're good. If you look at it and go "That's not quite right" because you learned something later after you started, then go back and clean it up.
At this stage, function is greater than form. Much of the form simply comes from experience.
Depends on what you want to do. Are you a successful web designer who's considering getting into the development side? Forge ahead, but tread cautiously. JavaScript can be easy to start with, but it can get ugly very quickly. And it's very different from any server-side language (including Java). Some of your JavaScript skills will translate to other languages, (conditional and control-flow operators, for example). But some things are unique to JavaScript and will require some relearning if you move to another language.
Also, some things in JavaScript won't completely make sense unless you've done object-oriented development; even though JavaScript is "prototype-based" rather than strictly object-oriented, without the OO concepts to relate to, the prototyping system may be difficult to understand. The typing system also may not make much sense if you don't have a lot of experience with different typing systems (static vs. dynamic, explicit vs. implicit).
Use a good framework like jQuery or YUI, but be sure to understand what's going on behind the scenes. Shog9's suggestion to use FireBug is a good one, too. It will show you what's going on (without having to do a lot of alert() statements in your code).
Your HTML DOM and CSS experience will help some, but only in the sense of understanding what the JavaScript is trying to do. Having written HTML and CSS by hand won't help you learn to write JavaScript; HTML and CSS are document markup languages, not imperative programming languages.
So go for it, but don't expect it to be easy. You may make a lot of quick progress, only to find that you're not as far along as you think, and that things don't work the way the appear to. But with enough effort and research you'll probably get there.
I think learning Javascript is a great idea if you are all ready doing HTML and CSS. Javascript is a cool, but quirky language. Most people that use don't really know how to write good JS code. I highly recommend watching Douglas Crockford video, see http://video.yahoo.com/watch/111593
They will give the real scoop on Javascript.
I've recommended JavaScript: The Good Parts before (and can't recommend it highly enough), but if you're new to programming I suggest starting with Head First JavaScript.
(source: oreilly.com)
I think you've got an abundance of great answers and resources already, but I'd like to chime in, too, since I've seen a couple of jQuery recommendations:
I love jQuery, too, and use it nearly daily. That said, for a beginner, I would recommend that you be comfortable with javascript proper first before diving into jQuery. Being comfortable with the syntax, variables, scope, and at least some DOM concepts will greatly improve your understanding of how to do what you want with jQuery. If you try to speed too quickly past the fundamentals, you'll definitely get stuck on some common misunderstanding that jQuery won't be able to help you with.
http://codeavengers.com level 1 JavaScript is great for the complete beginner. I created the courses and have had lots of great feedback from beginners who have found my course a fun and effective way to learn JavaScript.
Related
Is it just me or any JavaScript DOM manipulation or WEB UI Framework code is really hard to grasp because of long files, lack of proper indentation and scarcity of comments?
I have read couple good book on JavaScript and like the language, but when trying to understand the inner workings of all the popular frameworks I am having hard time to force myself to go beyond first hundred lines of a huge file.
This is a real question, not a statement. I am just trying to understand if I just suck or somebody else sharing my impressions.
Oh boy. First, stop trying to reverse-engineer minified and obfuscated javaScript. Second, it's open-source and documented.
Who said he is reading minified code?
This question might be closed, but yes, jQuery has some rather unreadable source and bad organization. Organization in that John Resig thought it was a good idea to throw everything onto a single constructor and its prototype.
I guess if you want a DOM library that is well commented, try looking at Prototype. It's actually very overcommented in my opinion, but if you want it as a reference for various DOM quirks and mechanics, it might be a good source.
The minified version is indeed not human-friendly, but it's smaller and faster. You're looking for the development version.
Whilst I can understand your frustration, jQuery (and other APIs, C++'s STL springs to mind) are not meant to be read by the average engineer. They are optimised for their purpose and excel at doing so, and that's why everybody uses them. Tried and tested.
Genarally jQuery uses a lot of closures and the notation of the framework as well as the plugins define a lot of anonymus functions on the go.
So it's not easy "following" the way of the data through the code. At least that is my limited understanding. So if You just suck, You're definetely not the only one.
The question is: Is it bad to learn how to do special effects, table sorting, etc, using jQuery instead of learning the bits of code that bring that alive with pure javascript?
I have previously addressed a similar problem in a question, but I missed adding this extra inquiry!
Yes you can. Doing it in JQuery isn't bad. Everyone uses some sort of Javascript library. I love JQuery. Your odds of making things that work in all browsers go up quite a bit, you get the UI done quicker, etc.
Though having a bit of Javascript knowledge is good, because when things go wrong you want to be able to debug the problem.
JQuery.com has lots of good tutorials.
You really should use jQuery; it will allow you to spend more time adding features instead of trying to make your code work in every browser (Note that even jQuery is not a silver bullet; you'll still have some cross-browser headaches in any non-trivial web app, especially if you need to support IE6).
There's no point in turning your back on new tools and libraries just to "stay close to the metal".
If you're afraid of lowering your value in your boss' eyes, look at it a different way. Would you prefer to hire a programmer who spends all of his time working around browser bugs, or a programmer who uses jQuery and finishes his projects faster because of it? Remember that managers are trying to ship products and make money, not simply hire elite programmers.
Personally I was recommended to learn JS before learning jQuery. But started off with jQuery, and can make pretty much with it without to much JS experience. What you do need to know of JS you can just google it and learn it when needed ;)
jQuery is fantastic for us that doesn't take the time to learn everything about JS
Personally, until the beginning of this year, I used to limit my use of javascript to only helping aid the user with things like web forms.
However, after playing around with jQuery for no more than a few days, I realised how much easier it made achieving javascript effects and functionality. Now I pretty much use jQuery on most web pages, a lot of the time, just to add nicer UI effects.
A background knowledge of raw javascript will never go amiss and you will almost certainly still have to mix it in with your jQuery scripts, but when you run into troubles, nearly every problem I've had, had a solution already posted on Stack Overflow or just on Google.
Not a very technical answer, but as an intermediate programmer, and javascript newbie I've had no problems learning to work with jQuery. The documentation and community are very helpful.
I think you should set yourself a goal of knowing javascript well enough to be able to author a plugin if you need it in your favorite framework. While using a framework is almost always the right way to go, there will be times when you can't find a plugin that does exactly what you need. At that point you need to know javascript well enough to be able to adapt a plugin to your needs or write your own.
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(I understand that someone else asked a similar question and it was closed as 'argumentative', but I'm really interested in understanding the arguments around this.)
I know JavaScript really well. I've been writing it professionally for years. I've internalized a lot of the cross-browser incompatibilities and sketchiness, know DOM manipulation like the back of my hand, have worked with some of the best web developers in the industry & picked up a lot of their mojo.
I've been checking out jQuery. I understand the point of a javascript library (how many times have I written animation, getElementsByClass, and hide/show functions?). But to be honest, it seems like a waste of time to learn an entirely new syntax that isn't less complex. It seems like I'd be bashing my head against a wall to learn an entirely new interface to the same old JavaScript.
I'm not technically an engineer, so maybe I'm missing something. Could someone spell out the tradeoffs of jQuery? Is it really faster to learn and understand jQuery syntax than to just learn JavaScript?
There are a few big benefits to using a framework over homegrown/handwritten code:
Abstractions. I'm sure you're very proud of the fact that you've slung enough JS to be able to write animations from scratch. You should be! However, abstracting common functionality away from yourself is actually very liberating. You just call the method and know the innards will be executed, and executed well. Even if you're very fast at writing the low-level stuff yourself, that's still time you've spent on that instead of solving today's problems.
Common language. Using a common framework is like speaking a common language. You can collaborate with other developers very easily, and each can pick up where others left off without friction. (Compared to stepping into an application which uses a homegrown library for the things jQuery can do.)
Experts. The people working on jQuery are JavaScript gods. I am really, really good at JavaScript, and you probably are too, but there's a big difference between normal good and jQuery good. A team of insanely good people are constantly poring over a small set of common functionality - tuning it, tweaking it, enhancing it to make it the best it can possibly be. That represents a huge number of man-hours a single person like you or me simply cannot reproduce, no matter how good we are. And if you are as good as the jQuery guys, you can only benefit by combining your talent with theirs and contributing to the jQuery codebase. It's a melting pot of insane talent.
I'm not technically an engineer, so maybe I'm missing something. Could someone spell out the tradeoffs of jQuery? Is it really faster to learn and understand jQuery syntax than to just learn JavaScript?
jQuery is more than "just another interface" to Javascript. It allows you to express yourself in ways that are more compact and succincter than the corresponding Javascript implementation. At the same time, it's clearer and much more powerful. Specifically, the benefits you get include:
Expressiveness. jQuery is essentially a DSL for DOM manipulation and querying. This specificity is a major source of its utility and effectiveness.
Cross-browser. To a very large extent, jQuery is "write once, run anywhere". Even in 2009, this is still a surprisingly rare feat for web-based platforms. It's gratifying and relieving to know that you won't have to waste time debugging obscure problems on IE6 (well, most of the time).
Highly complete documentation. As a developer, I prize APIs and frameworks that have taken the time to spell out what all the moving pieces are supposed to be doing. Nothing is more encouraging than knowing that (1) things are stable enough that writing documentation isn't an attempt to hit a moving target and (2) things are useful enough that they've attracted enough people to flesh out the documentation fully.
In sum, the difference between Javascript and jQuery is analogous to the difference between assembly and higher-order programming languages. Although they're both technically both "an interface to machine language" and can both do similar things, the latter is considered far more powerful because of how easy it is to represent things and develop rapidly.
One thing I don't see mentioned is that the library is written to work cross browser on a wide range of popular browsers and platforms: IE6+, Firefox 2+, Safari 3+
That alone is reason enough to use jQuery then to write your own JavaScript and have to worry about cross browser issues yourself.
You can't learn jQuery without learning JavaScript, and you can't be a jQuery guru without being a JavaScript guru.
That said, it really is much faster to do things with jQuery than with "bare metal" JavaScript. Moreover, the way one works with jQuery is at a far more abstract level than the way one works with "bare metal" JavaScript. In addition, the jQuery syntax is very basic and not at all hard to learn, although the way you think about jQuery is very different from the way you think about "bare metal" JavaScript but enables you do to much more, much more rapidly.
community support
other developers writting and testing code, make it possible for you to do things you simply do not have time to do. Its not about doing anything you do not know how to do, its about doing things quickly, efficiently, and of very high quality (its already been tested).
From the sounds of it, you know much of the same stuff that jQuery knows about the DOM, and I can only assume you've built-up a nice DOM toolset for yourself over the years that incorporates all of this knowledge. In short, No, you don't need to use jQuery. However, some of the rest of us do not know as much about the DOM, and jQuery levels the playing field so we can get on with getting work done for our clients.
That is not to say you should not learn jQuery (as opposed to using it). You may pickup a few things you didn't know. The 3 main features that distinguish it from other DOM libraries (including your own probably) are:
built-in support for CSS selector syntax, useful for finding elements
methods that operate on the set of wrapped elements
chaining. Every method in jQuery.prototype (with "setter" behaviour) returns this
Personally, 1) and 3) don't hold a high premium. But 2) turns out to be huge for me. I never realized until jQuery how much my code tended towards operating on a set of nodes rather than a single node (if someone would have asked me I would have guessed the opposite tendency). 2) virtually eliminated all for loops from my code (or .forEach or however else I tended to abstract it), which was actually quite liberating. Now I notice it's the rare occasion where my code must operate on some single element.
Speed of development and turnaround of code.
One thing I haven't seen mentioned in the other answers is that, eventually, someone else is going to have to maintain your code. If it's all custom, they'll have a rougher time of it than if a more standard library is used. If that's not of any concern to you, and you don't think you're likely to need any of the really slick jQuery modules, then keep on with what you're doing.
For me, there are several benefits, like speed of development, etc.
But at the end of the day, it boils down to one thing:
It removes a HUGE amount of the cross-browser BS that can eat up so much time and resources, so I don't have to deal with it
jQuery allows you to write shorter, cleaner code that's easy to understand. Many people use it, so there are many plugins that work along with it, minimizing bloat. The same may not be true of your own personal library.
If you know JavaScript really well you should also know that jQuery's syntax isn't different from JavaScript's syntax.
What you might be referring to is the chaining idiom (used everywhere in jQuery) which seems to make things look very different from other sort of code. Well there's a reason for that, it's because it bonds really well with how the DOM works.
If you truly know JavaScript, you'll be at running speed with jQuery in under a week's time. If you don't already know your way around JavaScript, adding a layer on top might do more harm than good. But that's just like anything else!
You're going to be writing better looking and easier to understand JavaScript at a faster pace and only once — not once per browser. Downside? You're going to tack on another ~50KB of JavaScript. That's what caching is for :)
Jquery is javaScript in the hand of the designer.
It is as easy as writing CSS styles on an element.
Also Jquery is the easiest to understand, write maintain, add plugins.
I was working on a gallery program for a client (which is now exhibiting inexplicable behavior in IE6 and 7 - surprise, surprise - but I found that when I switched from bare-metal Javascript to jQuery a lot of the work got much easier. To me, it makes available the CSS view of the DOM while writing Javascript - which makes traversal and manipulation much more intuitive. Also, the cross-browser compatibility and brevity is wonderful.
It doesn't really matter if jQuery is great or awful. It's the powerhouse JS library now, used on a huge number of pages, and future browsers will have to accommodate it or be seen as themselves buggy.
What I don't like about jQuery: I'm not that thrilled about how it ignores mobile phone browsers in its test suites. It gets pulled in on all kinds of pages on mobile phones, and yet it makes no effort to ensure it works well on them.
jQuery degrades gracefully and it's one of the fastest (not THE fastest anymore though):
http://mootools.net/slickspeed/
There are many other frameworks out there, and whichever you choose, you probably wouldn't go wrong, but having uses jQuery myself, I'd definitely recommend it.
:)
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Is it a good idea to learn JavaScript before learning a JavaScript framework library such as jQuery, Prototype, etc.?
Sometimes I find myself struggling because I feel I don't know JavaScript as well as I should.
An emphatic YES. It won't take as long to learn as you fear and the rewards will be more than worth it.
Sometimes I find myself struggling
because I feel I don't know Javascript
as well as I should?
I think you answered your own question.
I'll go against the grain and say that, while ideally you would become proficient in JavaScript before learning jQuery, you can probably make great progress on both fronts by jumping in and coding using the library.
One of jQuery's strengths is that it makes it easier to do certain things in the browser. You can get a lot of real work done by cutting and pasting and adapting other people's code, so why not start doing that? As you go, when you encounter an idiom you don't quite understand, dig around and find out what it means or how it works.
Over time, you will become a master of both JavaScript and jQuery.
If you have any kind of programming background, a good book to read to get you up to speed quickly on JavaScript is Douglas Crockford's, JavaScript: The Good Parts.
Long as you learn the BASICS in Javascript; HTML document traversing, event handling, etc... you should have no problem learning jquery.
Then from learning the basics you will understand how Jquery is to help you do the things that javascript can do, but with less work.
The answer to your question is a definitive yes. jQuery, Prototype and the rest serve to overcome cross-browser headaches and ease AJAX, UI behaviours, DOM operations etc. You'll end up with some pretty bad code if you are just copy/pasting snippets or have no real understanding of Javascript.
As a litmus test, you should be able to follow everything that is said in this wonderful re-introduction to Javascript. It's a bare minimum for writing good code and may require some more Googling on your part. Only then should you read Willison's equally good introduction to jQuery.
That should provide you a good start to build upon. And then if you feel up to it, you can start digesting Crockford (start with Douglas Crockford — JavaScript: The Good Parts).
Yes it a good idea because jQuery provides you with shortcuts for some methods and effects. By learning JavaScript you get the complete idea about how jQuery is working. It will help you to solve bugs and issues in future, when you will be working on a project.
Call me old-fashioned, but I think it is best to learn the basics of one tool before moving on to its advanced cousin -- much like being competent with a handsaw before moving on to a circular saw.
If you are struggling, you've answered your own question. I feel you'll be better equipped to make good use of JQuery once you are comfortable with JavaScript.
When I started my switch from VBScript to JavaScript I was immediately enthralled with Jquery. After a short while I started to really understand how JavaScript and Jquery interacted with each other and I became a little confused and frustrated. My issue was with the desire to use the simplicity of Jquery but I felt like I was cheating myself by not learning JavaScript first.
It turned out that I learned both at the same time. As I wrote JQuery routines I found the need to learn JavaScript in order to understand why things worked the way they did and to help make certain Jquery routines work correctly.
I am still learning JavaScript and Jquery but I am much less concerned about becoming a master of JavaScript as I know my understanding will grow as it needs to. It definitely helps to have some basic understanding of JavaScript but I would say you should focus on learning how to accomplish specific tasks and not on learning JavaScript before JQuery...
My $0.02 worth.
As I see it, jQuery is nothing but a framework to make your life simpler. jQuery itself is written in javascript. So it helps to learn javascript.
Mind you, you need not be a master but should be able to make the necessary changes /work arounds, when what you can do with jQuery alone is not sufficient.
To some degree, but don't get hung up on object oriented programming like in the java world (in javascript it's prototyping anyway). It would help in the long run to have a good understanding of closures/anonymous function and how the special variable "this" is used (particularly with regards to events such as click) and how functions like "apply" work. I'd also make sure that you really understood CSS selectors as they are a central feature of jQuery and pretty much every other JS framework out there.
You're also going to need to be familiar with how to use the full functionality of firebug.
I'd also assume you have a basic understanding or knowledge of how the DOM works.
That's the start of tinkering in Javascript.
The value proposition for jQuery (or any other framework) doesn't only come from what it does with javascript. It also builds on the DOM, HTML, and a number of language-agnostic patterns. And you don't need to understand it all in depth to find frameworks useful. Of course, you'll be better off if you know all the pieces, but we all need to start from something less.
I learned jQuery and javascript simultaneously, and it worked quite well for me that way.
I think the question isn't so much which to learn first, but more to the point, you need to expect to become increasingly familiar with all the pieces and how they work together.
To me it's somewhat (not entirely) the same question as what you need to know before starting with WebForms. Sure it's better if you're already comfortable with C# (and the same DOM and html), but it's legitimate to use WebForms as a vehicle for your education. Same thing can be said for frameworks.
Suppose you should know the following about Javascript:
How to calculate the X and Y element offset for the absolute/relative positioned DIV for browsers IE6-IE8, FireFox, Opera, Safari (each of the browser has different model for this particular case).
What is closure and how to create it.
How to create onLoad event in the browsers listed above.
Have an example of the HTML/Javascript code where you have pure HTML code like
Remove
and javascript code that add special handlers in automatic mode for A tag using "rel" attribute.
After you get acquainted with this you may use jQuery library that hide the complexity of this :)
Regards,
Pavel
I think learning events the document object model, and JavaScript forms programming is enough to get started in jQuery.
Of course, it goes without saying. How can you use jQuery if you don't learn JavaScript first? After all, jQuery is nothing but a library for JavaScript.
Yes.
You obviously don't need to learn everything about JS. But at least learn the basics, and try to learn some best practices.
For me the trickiest part about Javascript is all the different implementations of it in the different browsers. But there are certain things you can do to help yourself avoid some of those problems. For example, it's usually preferred to use document.getElementById() to access elements in the DOM since it essentially works the same way in all modern browsers. Also, it's almost always best to use feature detection rather than browser detection. Little things like that go a long way in avoiding problems in specific browsers later on.
Fortunately JQuery was written pretty well for cross-browser compatibility, but there may be times when you don't want to use it directly and you may have to rely on your JS skills.
There are really two seperate aspects to JavaScript within the Browser. First, the JavaScript Language, and second the HTML DOM that allows you to manipulate the page using the JavaScript Language.
That said, then YES you should spend time learning the JavaScript Language. I recommend picking up a copy of "JavaScript: The Good Parts" by Douglas Crockford.
Now as to the second part, the HTML DOM. You really don't need to focus too much on learning the ins and outs of the HTML DOM if you are going to use a framework like jQuery. Just do things the "jQuery way" and then pick up as much HTML DOM as is necessary along the way.
Just enough to debug your code. Otherwise, you will never be able to figure out what's not working.
Learning JS would make life easier for coding JQuery but I don't see why you should necessarily learn it first. You'll just have to learn it eventually.
My first thought was that It's always good to learn something new and Javascript is becoming ubiquitous (now is on the server side too ).
It's seems that you have still not decided the best answer for you and AFAIK this question was posted before March 21 ... I see plenty of time to read at least this that was written by a very talented guy.
If you study javascript you will never come to SO asking question like:
What the keyword this mean in the contest of my snippet of code?
But if you always are in a hurry, without having time to improve your code and If you never have to build jQuery plugins go without Javascript.
I am a .NET webdev using ASP.NET, C# etc... I "learned" javascript in college 5+ years ago and can do basic jobs with it. But I wonder if it is useful to become proficient in it.
Why should I learn Javascript?
Is it more advantageous then learning JQuery or a different library?
Yes, definitely learn Javascript before you learn one of the libraries about. It's the whole walk-before-you-can-run thing.
Make sure you add these sites to your bookmarks:
Mozilla's developer site: This contains the reference to the Javascript API in Mozilla. This will help you make sure you're writing code that Firefox understands.
IE's site in Microsoft Developer Network: The same, for IE.
W3's reference of DOM for HTML: In most web applications today, the Javascript code manipulates the DOM, which is an internal keeping track of the objects displayed on screen (but you already knew that, right ?) This is the reference to the DOM API. It is language neutral, which means it does not target Javascript, but these methods exist in Javascript too.
Douglas Crockford' site: Doug Crockford is THE MAN when it comes down to Javascript. The articles in his page are a must read. Because Javascript has closures and first-class functions, he believes it is closer to Lisp and Scheme than to other languages. And he teaches you how to greatly improve your code with these language features.
Yahoo Developer network: You may also want to check this. I'm not a regular visitor to this site, though, so I can't really say much about it.
Yes, absolutely you should learn JavaScript if you are doing web development. I highly recommend JavaScript: The Good Parts, by Doug Crockford. And, JQuery is a great framework to use (this site uses it) -- it kind of depends on what you are trying to do -- YUI and ExtJS are also very nice.
The answer is simple.
Hands down yes. There's a reason that Google have made such a big fuss about the V8 JS engine for Chrome, why Mozilla are working on TraceMonkey for Firefox and why Webkit have been working on Squirrelfish for a while (now Squirrelfish extreme). It's because JS is becoming more popular by the day.
Javascript is one of those languages that spending a few hours learning will probably teach you 99% of what you will ever really use. I would imagine you are at the point in your learning of javascript that you know more than enough now and just learn one or more of the frameworks now.
I would recommend brushing up on your non-frameworked javascript first. Refreshing/learning basic concepts of dom manipulation and what not. Like learning how to build a linked list, stack or queue in C++ before learning how to use the STL (standard template libraries).
In addition to brushing up on straight javascript, it might be good to get into a framework that doesn't abstract and change the way things work so much, for instance Prototype. You code with it very much the same way you code with straight javascript. Read through the Prototype code, learn how to make classes, and do some fancy stuff. From experience, I can say reading through the Prototype.js helped me learn alot.
After messing around a bit, then I'd say go for jQuery. If jQuery didn't, literally, change the way you write code I'd say go for it first, but learning how to build classes and js inheritance and what not can be a very important lesson for someone who wants to become fluent in JS.
Learning javascript is recommended for any web application developer. Why?
You will better understand the possibilities, limitations and dangers related to developing a web application
It is a boost for your career, if you are working on a web application that has a user interface.
However, learning javascript is usually a trade-off between a programming language and another. You should consider whether javascript is relevant for your career or project.
Unless you want to really get into javascript, I think you'd be better off learning enough JS to leverage one of the tried and tested javascript libraries out there.
One thing nice about JavaScript is that it is quite different from mainstream languages such as C#, VB.NET or Java. Learning it, especially if you have occasions to use it, will give you another insight on programming, and that's always good. I think it's worth learning it.
If you are doing web development then at some point you are going to get exposed to Javascript or ECMAScript at some point in your career for any one of a number of reasons. At a minimum you should know enough Javascript to be able to be able to validate user input; however, the web is moving in the direction of using more an more Ajax so you should also know enough Javascript to properly leverage one of the major libraries out there such as jQuery.
As some of the other users have noted, you can learn most of what you need of Javascript on a day to day basis in a single day or a couple of afternoons. If you want to get more advanced with Javascript then you are going to have to invest much more time in learning the language but odds are that unless you seek out this type of work that you are not going to encounter something that a preexisting library doesn't already exist for.
If all you want is to do some simple UI-effects and the like, I suggest you just pick a library and go for it!
Using libraries eliminates all the flawed implementations of JavaScript and provides you with an API which is the same across all browsers. And if you're working together with others it is also a great way of implementing code-standards and best practices.
Learning a second programming language is always good.
By the sound of it, JavaScript is a language that you use, to it will be of practical use too. As a web dev, it has been recommended to me in a review that i learn at least basic JavaScript.
A library such as jQuery is essential for web development thse days, so you could learn that too.
I don't think a lot of deliberate learning makes sense (but of course you need some basic knowledge), but I also think after some years of web development you'll become pretty proficient in the language anyway :)
If you are a webdev then yes, you should be proficient with Javascript. Javascript is a major part of making web apps as interactive as desktop apps.
With that being said, learn to use one of the cross-browser compatible libraries like JQuery, Prototype, etc. We do not need to have any more single browser crud created using Javascript, just because any real man/woman rolls their own.
A few things to learn in Javascript:
1. Basic syntax
2. The various flavours of function declaration.
3. Passing functions around and how to use passed in functions.
I recommend Jeremy Keith's books: DOM Scripting and Bulletproof Ajax. After you become more fluent in JS I would recommend a JS library(I use jQuery, but that is not important).
JS is important to learn. You cannot use a framework without the proper understanding of how it works. That is doing things backwards.
i thing you should have a good knoloedge base of language specification and DOM (Document Object Model). it means,you shoud know how find/create "page object" an edit properties. Also you should have an idea of "object oriented" javascript tecniques, which the starting point of a lot of framework. you don't need learn specific framework if you don't use it. simple keep in mind generic base concept!
I'll go with the opposite answer most are putting out there. Learning javascript as a developer these days is almost pointless. The language is similar enough to java/C# that it's syntax and semantics shouldn't be lost on you.
What you should learn is jQuery.
As you use jQuery you'll pick up the most common things you'll ever need from javascript anyway.
If you're involved with the Web in anyway then the answer is "Yes, always". Maybe an embedded or system's programmer could get by without JavaScript, but not a webdev.
Most of the libraries are designed to alleviate some of the pain of interacting with a multitude of browsers. They will not abstract away core JavaScript functionality.
Yes, you should learn JavaScript. Sooner or later you will need to use it!