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Many years back, I was told that Javascript was harmful, and I remember being annoyed with endless popup when I right-clicked an image to download it.
Now it seems suddenly that Javascript is great, and you can do a lot of things with it to let users have native-like web application experience.
I admit I have missed 6-7 years of Javascript literature, so I hope to start anew with SO kickstarting me to understand the following:
Is Javascript mainly concerned about user interface i.e. smoothen interaction between application and users and not about logic processing, number crunching or form processing etc.?
Can Javascript write to local hard drive (besides cookies)?
Can Javascript web application run with Javascript capabilities in browsers turned off? (I would think outright no, but an article on Adaptive Path said 'maybe')
Is AJAX illegal to use due to Eolas patent claim? Is it worth it spending effort learning it when the future is not secure? (I know AJAX is not Javascript)
Thanks. Hoping for enlightenment.
Yes. JavaSscript is usually used to enhance the user's experience and make the site easier to use. It is also possible to delegate validation tasks and the like to JavaScript, however (though this should never absolve the server of its responsibility to check input).
No.
That depends on how the application is written. If it's done properly, then the JavaScript will merely enhance the interface, and the application will still work without it; this is called progressive enhancement.
Not at all. AJAX is used extensively on this very site!
One reason for the resurgence of popularity for JavaScript lately is the emergence of several frameworks. These make the process of writing JavaScript much, much easier, allowing tasks that would previously have been horribly complex to be implemented with minimal time and effort. The most popular of these is jQuery, which is a good place to start if you're intending to get in on the action.
Overall, JavaScript is a very powerful tool that allows you to create very rich interfaces. Well worth learning.
Yes, Javascript is all about client side processing, but also about AJAX where it calls back to the server asynchronously so that users do not see pages reloading.
No
No, but there are ways to gracefully degrade the experience for non javascript users. It requires carefult planning however.
No, that lawsuit was just about the browser technology that enables it. As a developer you dont have to worry about that.
Can Javascript write to local hard drive (besides cookies)?
Not really. However, as HTML5 support becomes more widespread you'll be able to use things like Web Storage and Web SQL. You won't be able to write arbitrary files on the user's hard drive, but using those two technologies you'll be able to persistently store and access data.
Can Javascript web application run
with Javascript capabilities in
browsers turned off? (I would think
outright no, but an article on
Adaptive Path said 'maybe')
It really depends on how you define "web application." You can write web apps without using Javascript for anything but UI candy, in which case you can degrade gracefully without without it. However, it's also possible to write web apps that rely heavily (entirely, even) on Javascript, which will utterly fail without it.
Is AJAX illegal to use due to Eolas
patent claim? Is it worth it spending
effort learning it when the future is
not secure?
I'm not a lawyer, but I'd agree with the other answers -- you shouldn't worry about it. I'm certainly still writing AJAX stuff :)
Is Javascript mainly concerned about
user interface i.e. smoothen
interaction between application and
users and not about logic processing,
number crunching or form processing
etc.?
It's about both. And more than that.
Javascript has really come into its own in the past few years. Browsers have gotten a lot faster at executing it quickly, and people have been figuring out new ways to use the language itself to its full potential. You can really start using Javascript like a full-out application programming language, and not just to write little scripts that animate something or validate input.
If you're just getting back into the language and haven't read Crockford yet, I would highly recommend it. It's a great starting point to realizing the full potential of Javascript.
Edit: Some good Crockford Links
Javascript: The World's Most Misunderstood Programming Language
Javascript: The Good Parts (This is a presentation. Crockford also wrote a book by the same name that I haven't read myself, but I hear it's quite excellent.)
It's mainly for UI, but it can be used to save server-time on some operations (for example, Mathoverflow uses it to render LaTeX) and it's becoming popular to do so. But when you do this, you need to be respectful of the end-users time, because JavaScript can hold up some browsers, while it runs. But in general, it's a good and interesting idea.
Not without permission
If it's written correctly, it can. It's called "Graceful degredation" (some other variant terms exist, but the idea is the same). The basic idea is that you have it such that the JavaScript fails 'gracefully', and links that would normally get handled via JavaScript (i.e. to do some inline next-paging) will navigate to a 'backup' page that shows the relevant content.
I don't know about that, but AJAX can be implemented in different ways, XMLHTTPRequest is just one of them :) (And the most common, and suitable). Generally you like a library do this for you anyway (jQuery, or otherwise) but you can do it yourself for fun.
Yes, in my experience JavaScript is generally used to create a streamlined interface and relays information from the client to a server application for processing.
Yes, if the browser is configured to allow this (most aren't by default since this can be very dangerous).
No, JavaScript will not run if the browser is configured to have JavaScript disabled.
I wouldn't forgo learning JavaScript for this reason - as for the legality of the whole thing I wouldn't feel comfortable advising you about this. Still I think JavaScript is worth learning in spite of this situation.
The Eolas patent covers the embedding of objects in a HTML document (see US patent 5,838,906 titled "Distributed hypermedia method for automatically invoking external application providing interaction and display of embedded objects within a hypermedia document") ... this scope would not seem to include AJAX as a suite of technologies (being essentially scripting in a document to load content elements).
Partial answers:
I think all the security vulnerabilities associated with javascript have been fixed? IIRC the problems weren't with javascript, they were with particular browser's implementation of javascript.
I wouldn't worry about any patent claims on the AJAX technology. Patent sueing and counter-sueing is common place in the software world and invariably ends up with the affected parties licencing each other's technology. AJAX is not going anywhere :)
I'm looking for a way to write a non-GUI bot using Mozilla Framework. The bot should be able to work like normal browser (automatically download relevant JS files, make XMLHTTPRequests, run JS operations, modify DOM), except no GUI will be needed.
I wonder if it is possbile to build XULRunner without X, GTK/KDE (without any GUI dependencies), as I will run the bot on FreeBSD server 6.4.
It may sound a bit weird but I need a bot with capacity to operate like browser, runs JS, modifies DOM, submit forms running on non-GUI environments.
I've looked into other browsers such as Lynx, Links, Hulahop, Chrome V8 engine, WebKit JavascriptCore but yet to find desirable output.
It's a part of school project, thesis. We will use to observe price change of budget airlines and after one year long data collection, we need to deduce pricing strategy and customer behavior. It is a serious Final Year Project.
Any hint or help is greatly appreciated! Thank you in advance!
Regards.
You should be able to make progress with selenium. It's a record/test/play tool but its core is manipulating the DOM.
Update from Grundlefleck's comment: As for launching the actual tests there is selenium remote-control, which allows you to write your tests in Java, Ruby, plain HTML and other possible drivers.
Yes, it is possible (but it might very well require LOTS of code changes).
No, I do not know any of the details.
I would not recommend this approach for your purposes. From your comment, it sounds like you are trying to scrape webpages. If you really need to use JavaScript, you can use a stand-alone JavaScript-engine (Mozilla's is available here). Otherwise, I would use Beautiful Soup with Python or Twill. You might also want to read this question.
I come from the Microsoft world (and I come in peace). I want to rapidly prototype a web app and if it works out, take it live - and I don't want to use ASP.Net.
I am not sure which web application toolkit to use though. Should I use GWT, DOJO...other recommendations? I am open to any server-side language but am looking at RoR, Php or even Java (J2EE to be precise). I am not much of a Javascript/CSS guy so a toolkit that might make it relatively easy on me on those fronts would be preferable.
Also, I am a mac user at home. What IDEs go along with the framework you would recommend?
Any recommendations guys?
If you're open to doing Java, GWT is the way to go. It allows you to have a relatively uniform codebase across client-server, and to only use one language on both.
There are some limitations to doing very off-the-beaten-path AJAXy things (which GWT makes difficult, but not impossible), but it doesn't sound like that's your use case anyway.
GWT will allow you to scale up by using more of its features as your app gets more complex - and your prototype won't be throwaway code.
If you want to write the front and back end in JAVA, and want to do complex ajax type thing, then GWT is a great way to go.
The easiest way to think about it is that building a GWT app is kind of like building a JAVA swing application that hooks into a server. Just like a swing app that uses a server you can make it fat or thin. When you're done it all compiles down into HTML and javascript, and has very good modern browser support (ie6+ ff, opera, safari).
It does abstract all the javascript and HTML away, but if you want it to look good you'll still need to understand CSS.
I think anyone who says that that it ruins MVC or that it's a muddying of client vs server doesn't understand GWT. GWT is a CLIENT side framework. And it is only used on the CLIENT. GWT does provide an RPC mechanism to hook it into JAVA (and other) back ends, but that's just a communication protocol, it doesn't mean that your server code magically becomes your client code. Sure you can write a whole bunch of business rules into your UI if you really wanted to, but you can do this with any framework, so it would be silly to say that GWT is somehow different in that respect.
GWT is a good choice, while if you choose more powerful JavaScript framework based on GWT (e.g. SmartGWT), the compiled stuff is too heavyweight.
Choose direct JavaScript if you need a compact project.
I am a fan of GWT, however I am very familiar with Java. I found it to be intuitive, and surprisingly easy to get good results quickly. If you are to use GWT, then you'll definitely want to use the free, and immensely powerful Eclipse IDE.
One disadvantage of GWT is that it requires Javascript to be supported by the browser, there is no "graceful degradation".
We have evaluate a large list of frameworks and have decide us for Echo2.
You need only to code in Java. Javascript you need only if you want write your own components.
There are no startup performance problems with large projects like GWT.
You can use the full range of Java in your client code because it run on the server. In GWT you can use only very small set of Java classes.
The IDE for Java is Eclipse. This is independent of the used framework.
I'm a fan of jQuery, the chainability of actions, traversals, and commands is really powerful. A good friend of mine is crazy about Mootools, he works at a Java shop FWIW. He mentioned a cool feature of Mootools is that you can specify the functionality you want the framework to include and it will generate the entire library on a single line in a file that you can include on your page to minimize the weight of the framework (pretty cool feature). Really it just depends on what you are most comfortable with. jQuery has great tutorials, is super fast, and can be used along with other javascript frameworks.
Not related to GWT, but have you considered other backends that GWT could work nicely with?
Grails is one backend that ties quite nicely with GWT.
Personally, I would avoid server-side frameworks that try to embed or hide the client-side framework. I'm sure that GWT is great for getting something going quickly, and is probably fine for certain kinds of applications, but you'll probably run into lots of problems "on the edges" for more complex applications. Decoupling the client framework from the server-side framework avoids those problems.
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Does anyone see server-side JavaScript taking off? There are a couple of implementations out there, but it all seems to be a bit of a stretch (as in, "doing it BECAUSE WE CAN" type of attitude).
I'm curious to know if anyone actually writes JavaScript for the server-side and what their experiences with it have been to date.
Also, which implementation is generally seen as the most stable?
I like to read Googler Steve Yegge's blog, and recently I came across this article of his where he argues that Mozilla Rhino is a good solution for server-side JS. It's a somewhat sloppy transcript, you might prefer to watch the video of the talk. It also offers a little bit of insight on why he thinks server-side JS is a good idea in the first place (or rather, why he thinks that it's a good idea to use a dynamic language to script Java). I thought the points he makes were convincing, so you might want to check it out.
A while earlier, he also posted something about dynamic languages in general (he's a big fan of them), just in case you were wondering why to use JS at all.
Why would you want to process
something in Javascript when you can
process it in PHP or ASP.NET which are
designed specifically for this task?
Perhaps because JavaScript is a more powerful programming language than those two? For example, it has functions as first-class data types and support for closures.
Steve Yegge has blogged about porting Ruby on Rails to server-side JavaScript as an internal project within Google ("Rhino on Rails"). He did it because he likes Rails but using Ruby isn't allowed within Google.
Before it was acquired by Google, JotSpot used server-side JavaScript to let you query their database and display your pages. They used Rhino to do it. CouchDB uses server-side JavaScript to create views of their database.
As you can see from these examples, a great way to use JavaScript on the server is for plugins. One of the reasons it's used is that you can create a very isolated sandbox for people to run their code in. Also, because of the way that JavaScript as a language works, you can provide a user tooling specifically honed to the tasks your users need to complete. If you do this right, users don't need to learn a new language to complete their tasks, a quick glance at your API and examples is enough to get them on their way. Compare this to many of the other languages and you can see why using server-side JavaScript to provide a plugin architecture is so enticing.
A secondary popular solution, one which can be seen through a project like Jaxer, is that a common problem of web applications that do client-side validation is that, since JavaScript is easily bypassed in the browser, validation has to be run once again on the server. A system like Jaxer allows you to write some validation functionality that is reusable between both server and client.
Support for JS on the server has been getting stronger and the number of frameworks is getting bigger even faster.
Just recently the serversideJS group was founded. They have a lot of smart people that have been working on serverside JS for years (some of them more then 10).
The goal for this project is to create
a standard library that will
ultimately allow web developers to
choose among any number of web
frameworks and tools and run that code
on the platform that makes the most
sense for their application.
to the people who say "why would you choose JS over java or any other language?" - you should read this Re-Introduction by Crockford and forget about the DOM - the DOM is superugly, but that's not JS fault and JS is not the DOM.
I've never even heard of this, but it strikes me as using the wrong tool for the job. Since programming languages are just tools designed to help us solve some problem.
Why would you want to process something in Javascript when you can process it in PHP or ASP.NET which are designed specifically for this task?
Sure you can pound a nail in with a screw driver, but a hammer works much better because it was actually designed for it...
So no, I don't see it taking off.
Well, plain ol' ASP supported JavaScript server-side years ago and everyone onad their dog used VBShiate instead. But I have to agree with the others: JS does not seem to be the right tool here - and I love to do client-side JS :)
I personally did a whole site in server side JavaScript using ASP. I found it quite enjoyable because I was able to have some good code reuse. This included:
validation of parameters
object modeling
object transport
Coupled with a higher-level modeling tool and code gen, I had fun with that project.
I have no numbers on perf unfortunately, since it is used only on an intranet. However, I have to assume performance is on par with VBScript backed ASP sites.
It seems like most of you are put off by this idea because of how unpleasant the various client-side implementations of Javascript have been. I would check out existing solutions before passing judgment, though, because remember that no particular SS/JS solution is tied to the JS implementations currently being used in browsers. Javascript is based on ECMAScript, remember, a spec that is currently in a fairly mature state. I suspect that a SS/JS solution that supports more recent ECMA specs would be no more cumbersome than using other scripting languages for the task. Remember, Ruby wasn't written to be a "web language" originally, either.
Does anyone see Server-side Javascript
taking off?
Try looking at http://www.appjet.com a startup doing hosted JavaScript applications to get a feel for what you can do. I especially like the learning process which gently nudges the user to build things with a minimal overhead ~ http://appjet.com/learn-to-program/lessons/intro
Now it might seem a weird idea at the moment to use JavaScript but think back when PC's started coming out. Every nerd I knew of was typing away at their new Trash-80's, Commodore64's, Apple ]['s typing in games or simple apps in BASIC.
Where is todays basic for the younger hacker?
It is just possible that JavaScript could do for Web based server side apps as BASIC did for the PC.
XChat can run Javascript plugins.
I've some accounting software completely written in Javascript.
There's this interesting IO library for V8: http://tinyclouds.org/node/
CouchDB is a document database with 'queries' written in Javascript (TraceMonkey).
Considering this, i believe, server-side Javascript did take off.
Server-side programming has been around for a lot longer than client side, and has lots of good solutions already.
JavaScript has survived and become popular purely because developers have very little choice in the matter - it's the only language that can interact with a DOM. Its only competition on the client side is from things like Flash and Silverlight which have a very different model.
This is also why JavaScript has received so much effort to smart it up and add modern features. If it were possible for the whole browser market to drop JavaScript and replace it with something designed properly for the task, I'm sure they would. As it stands Javascript has strange prototype-based objects, a few neat functional programming features, limited and quirky collections and very few libraries.
For small scripts it's fine, but it's a horrible language for writing large complicated systems. That things like Firefox and Gmail are (partly) written in it is a heroic accomplishment on their part, not a sign that the language is ready for real application development.
Flash Media Server is scripted by using Server Side Action Script, which is really just javascript (ECMAScript). So, I do it a lot. In fact, most of my day was dealing with SSAS.
And I hate it. Though to be fair, a bunch of that is more related to the (not so great) codebase I inherited than the actual language.
I think server-side Javascript is guarenteed to take off. Its only a matter of time.
Mozilla, Google, and Adobe have so much vested interest for Javascript that it would take a miracle to dislodge it from the browser world. The next logical step is to move this into the server-side.
This is a step towards moving away from the hodge podge of Internet technology that usually includes all of these
HTML
CSS
Javascript
Serverside Language J2EE/ASP/Ruby/Python/PHP
SQL
I haven't heard much about the current state of Javascript Server frameworks, except that they are mostly incomplete.
I see server-side js will offer considerable advantages in future applications. Why? Web apps that can go offline, client-side db store, google gears, etc...
Following this trend, more and more logic are moving into the client-side. Use an ORM that works for client-side, and use another on server-side (be it PHP / Ruby / whatever), write your synchronization logic twice in two different languages, write your business logic twice in two different languages?
How about use js on the client AND the server side and write the code once?
Convincing?
Personaly i've been developing and using my own JavaScript framework for about 4 years
now.
The good thing about JS on serverside is that implemented in ASP Classic you don't need
any other plugin or software installed, besides i'm also using my javascript (client)
framework on my server, that allows me to enjoy of the same functionality and proven
performance of my functions at both environments client and serverside.
Not only for data validation, but also lets say HTML or CSS dynamic constructions
can be done client or serverside, at least with my framework.
So far it works fast, i have nothing to complain or regret except its great usability
and scalability that i have been enjoying during this past 4 years, until the point
that i'm changing my ASP Classic code to javascript code.
You can see it in pratice at http://www.laferia.com.do
Node.js has taken off and proven that server-side JavaScript is here to stay =)
I can't see most developers getting over their distaste for client-side JavaScript programming. I'd rather go to Java for server-side stuff before choosing JavaScript.
With the increased power of JavaScript frameworks like YUI, JQuery, and Prototype, and debugging tools like Firebug, doing an application entirely in browser-side JavaScript looks like a great way to make simple applications like puzzle games and specialized calculators.
Is there any downside to this other than exposing your source code? How should you handle data storage for this kind of program?
Edit: yes, Gears and cookies can be used for local storage, but you can't easily get access to files and other objects the user already has around. You also can't save data to a file for a user without having them invoke some browser feature like printing to PDF or saving page as a file.
I've written several application in JS including a spreadsheet.
Upside:
great language
short code-run-review cycle
DOM manipulation is great for UI design
clients on every computer (and phone)
Downside:
differences between browsers (especially IE)
code base scalability (with no intrinsic support for namespaces and classes)
no good debuggers (especially, again, for IE)
performance (even though great progress has been made with FireFox and Safari)
You need to write some server code as well.
Bottom line: Go for it. I did.
Another option for developing simple desktop like applications or games in JavaScript is Adobe AIR. You can build your app code in either HTML + JavaScript or using Flash/Flex or a combination of both. It has the advantage of being cross-platform (actually cross-platform, Linux, OS X, and Windows. Not just Windows and OS X).
Heck, it may be the only time in your career as a developer that you can write a web page and ONLY target ONE browser.
SproutCore is a wholly JavaScript-hosted application framework, borrowing concepts particularly from Cocoa (such as KVO) and Ruby on Rails (such as using a CLI generator for your models, views and controllers). It includes Prototype, but builds plenty of stuff such as sophisticated controls on top of that. Its Photos demo is arguably impressive (especially in Safari 3.1).
Greg already pointed you to Gears; in addition, HTML 5 will come with a standardized means of local storage. Safari 3.1 ships with an implementation where you have a per-site SQLite database with user-settable size maximums, as well as a built-in database browser with SQL querying. Unfortunately, it will be a long time until we can expect broad browser support. Until then, Gears is indeed an alternative (but not for Safari… yet!). For simpler storage, there is of course always cookies.
The downside to this would be that you are at the mercy of them having js enabled. I'm not sure that this is a big deal now. Virtually every browser supports js and has it enabled by default.
Of course the other downside would be performance. You are again at the mercy of the client handling all the intensive work. This also may not be that big of a deal, and would be dependent on the type of app you are building.
I've never used Gears, but it looks like it is worth a shot. The backup plan would be to run some server side script through ajax that dumps your data somewhere.
Not completely client side, but oh well.
Nihilogic (not my site) does a lot of stuff with Javascript. They even have several games that they've made in Javascript.
I've also seen a neat roguelike game made in Javascript. Unfortunately, I can't remember what it was called...
If you want to write a standalone JavaScript application, look at XULrunner. It's what Firefox is built on, but it is also built so that you can distribute it as an application runtime. You will write some of the interface in JavaScript and use JavaScript for your code.
Gears might provide the client-side persistent data storage you need. There isn't a terribly good way of not exposing your source code, though. You could obfuscate it but that only helps somewhat.
I've done simple apps like this for stuff like a Sudoku solver.
You might run into performance issues given that you're completely at the mercy of the client's Javascript interpreter. Gears would be a nice way of data storage, but I don't think it has penetrated the market that much. You could just use cookies if you're not fussy about that kind of thing.
I'm with ScottKoon here, Adobe AIR is great. I've really only made one really nice (imho) widget thus far, but I did so using jQuery and Prototype.js, which floored in such wonderful ways because I didn't have to learn a whole new event model. Adobe AIR is really sweet, the memory foot print isn't too bad, upgrading to a new version is built into AIR so it's almost automatic, and best of all it's cross-platform...they even have an alpha-version for Linux, but it works pretty well already on my Eee.
Standalone games in GWT:
http://gpokr.com/
http://kdice.com/
In regard to saving files from a javascript application:
I am really excited about the possibilities of client-side applications. Flash 10 introduced the ability to create files for save right in the browser. I thought it was super cool, so I built a javascript+flash component to wrap the saving feature. Right now it only works for creating text based files (vcard, ical, xml, html, css, etc.)
Downloadify Home Page
Source Code & Documentation on Github
See It In Use at Starter for jQuery
I am looking to add support for non-text files soon, but this is a start.
My RSS feeds have served me well- I found that Javascript roguelike!
It's called The Tombs of Asciiroth.
Given that you're going to be writing some server code anyway, it makes sense to keep storage on the server for a lot of domains (address books, poker scores, gui configuration, etc.,.) For anything the size of what you'll get in Webkit or Gears, you can probably also keep it on your server.
The advantage of keeping it on your server is two-fold:
You can integrate it fairly simply as a Model layer in a typical MVC framework, and,
Users get a consistent view without being tied to their browser/PC, or in a less-than-ideal environment (Internet Cafés).
The server code for handling this can also be fairly trivial, particularly if it's written with this task in mind, so it's not a huge cognitive burden.
Go with qooxdoo. They recently realsed 1.0, although most users of it say it was ripe for 1.0 at least two versions ago.
I compared qooxdoo with YUI and ext, and I think qooxdoo is the way to go for programmers - YUI isn't that polished as qooxdoo, from a programmer's point of view and ext has a not so friendly licensing model.
A few of the strong points (for me) of qooxdoo are:
extremely clean code
the nicest OO programming model I've seen among Javascript frameworks
an extremely rich UI widget library
It also features a test runner for unit tests, an API doc generator and reader, a logging facility, and several useful features for debugging, grouped under something called Inspector.
The only downside is that there aren't readymade themes (something like skins) for qooxdoo. But creating your own theme is quite easy.