JavaScript is the original and common name applied towards most flavors of a scripting language that originated on NetScape Navigator. Use this tag for questions regarding common implementations of ECMAScript, JavaScript, JScript, etc. JS does not typically refer to its ECMA-cousin, ActionScript.

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215
votes
7answers
17k views

Does using == in JavaScript ever make sense?

In JavaScript, the Good Parts, Douglas Crockford wrote: JavaScript has two sets of equality operators: === and !==, and their evil twins == and !=. The good ones work the way you would expect. ...
179
votes
3answers
59k views

Pros and Cons of Facebook's React vs. Web Components (Polymer)

What are the main benefits of Facebook's React over the upcoming Web Components spec and vice versa (or perhaps a more apples-to-apples comparison would be to Google's Polymer library)? According to ...
92
votes
15answers
13k views

Why did memory-managed languages like Java, Javascript, and C# retain the `new` keyword?

The new keyword in languages like Java, Javascript, and C# creates a new instance of a class. This syntax seems to have been inherited from C++, where new is used specifically to allocate a new ...
84
votes
2answers
6k views

What is JavaScript, really?

All this started when I was looking for a way to test my webpage for JavaScript conformance like the W3C HTML Validator. I have not found one yet. So let me know if you know of any... I looked for ...
74
votes
23answers
6k views

How do developers find the time to stay on top of latest technologies? [closed]

I was a freelance web developer until circa 2004 when I started going down the management route but have decided to try to get back into development again (specifically JavaScript and HTML5 web/mobile ...
71
votes
20answers
19k views

Should I bother to develop for JavaScript disabled? [duplicate]

Should I bother to develop for JavaScript disabled? I feel that my time is better spent developing for the majority.
69
votes
27answers
9k views

How important is graceful degradation of JavaScript?

Should web developers continue to spend effort progressively enhancing our web applications with JavaScript, ensuring that features gracefully degrade, thereby ensuring accessibility? Or should we ...
58
votes
14answers
6k views

Is it a bad idea to return different data types from a single function in a dynamically typed language?

My primary language is statically typed (Java). In Java, you have to return a single type from every method. For example, you can't have a method that conditionally returns a String or conditionally ...
53
votes
3answers
6k views

Why do JavaScript frameworks/libraries have functions which already exist in pure JavaScript?

I wonder why frameworks/libraries have their own helpers although they exist natively already. Let's take jQuery and AngularJS. They have their own each iterator functions: jQuery.each() ...
53
votes
2answers
6k views

Are there any OO-principles that are practically applicable for Javascript?

Javascript is a prototype-based object oriented language but can become class-based in a variety of ways, either by: Writing the functions to be used as classes by yourself Use a nifty class system ...
52
votes
8answers
8k views

Client-side coding: How to prevent malicious use?

Over the last few years, the trend for client-side (browser) applications has really taken off. For my latest project, I have decided to try and move with the times and write a client-side ...
46
votes
6answers
40k views

Advantages of using pure JavaScript over JQuery

What are the advantages of using Javascript-only versus using JQuery-only? I have limited experience with JavaScript and JQuery coding. I've added bits and snippets of each to HTML pages but I've ...
44
votes
2answers
23k views

When not to use Google Web Toolkit? [closed]

I'm considering use of GWT on a major in-house web app development project, namely it's major advantage in my eyes is the cross-compilation to Javascript which would (at least theoretically) help my ...
43
votes
13answers
7k views

Is it considered bad practice to have PHP in your JavaScript

So many times on this site I see people trying to do things like this : <script type="text/javascript"> $(document).ready(function(){ $('<?php echo $divID ?>').click(funtion(){ ...
43
votes
6answers
3k views

How safe are hidden AJAX requests that fake performance?

What is a hidden AJAX request? I've noticed an increase in the usage of hidden AJAX requests designed to make a user's action appear to happen immediately. I'll refer to this type of AJAX request as ...
42
votes
8answers
5k views

How do I get started with HTML5? [closed]

What is the recommended workflow to learn HTML5? What tools should I install? What SDK? Where to start? How to test? How to debug? What do I read? I understand that what is often labelled as "HTML5 ...
42
votes
8answers
22k views

Why do people disable JavaScript?

I asked a question yesterday Should I Bother to Develop For JavaScript Disabled?. I think the consencus is: Yes, I should develop for JavaScript Disabled. Now I just want to understand why users ...
41
votes
13answers
9k views

How does Python's handling of line-breaks differ from JavaScript's automatic semicolons?

Javascript has a feature called Automatic Semicolon Insertion where basically if the parser encounters an invalid token, and the last token before that was a line break, then the parser will insert a ...
41
votes
6answers
11k views

What are the pros and cons of Coffeescript? [closed]

Of course one big pro is the amount of syntactic sugar leading to shorter code in a lot of cases. On http://jashkenas.github.com/coffee-script/ there are impressive examples. On the other hand I have ...
41
votes
11answers
4k views

Is there any reason not to go directly from client-side Javascript to a database? [duplicate]

Possible Duplicate: Writing Web “server less” applications So, let's say I'm going to build a Stack Exchange clone and I decide to use something like CouchDB as my backend store. If I use ...
40
votes
4answers
46k views

Reasons NOT to use JSF [closed]

I am new to StackExchange, but I figured you would be able to help me. We're crating a new Java Enterprise application, replacing an legacy JSP solution. Due to many many changes, the UI and parts of ...
38
votes
5answers
7k views

Why aren't there native Javascript interpreters for Windows/Mac/Linux?

It seems to me it would be very useful to use Javascript for general server side scripting tasks as it has more or less the same features as Perl and Python. But AFAIK there are no generally available ...
37
votes
6answers
2k views

Why not embed styles/scripts in HTML instead of linking?

We concatenate CSS and JavaScript files to reduce the number of HTTP requests, which improves performance. The result is HTML like this: <link rel="stylesheet" ...
35
votes
3answers
6k views

What's so bad about the DOM?

I keep hearing people (Crockford in particular) saying the DOM is a terrible API, but not really justifying this statement. Apart from cross-browser inconsistencies, what are some reasons why the DOM ...
34
votes
16answers
4k views

Should I continue my self-taught coding practice or learn how to do coding professionally? [closed]

Lately I've been getting professional work, hanging out with other programmers, and making friends in the industry. The only thing is I'm 100% self-taught. It's caused my style to extremely deviate ...
34
votes
2answers
3k views

Strategy for generating unique and secure identifiers for use in a “sometimes offline” web app

I have a web based project that allows users to work both online and offline and I'm looking for a way to generate unique ids for records on the client side. I'd like an approach that works while a ...
33
votes
5answers
7k views

How easy is it to hack JavaScript (in a browser)?

My question has to do with JavaScript security. Imagine an authentication system where you're using a JavaScript framework like Backbone or AngularJS, and you need secure endpoints. That's not a ...
33
votes
4answers
6k views

The importance of Design Patterns with Javascript, NodeJs et al

With Javascript appearing to be the ubiquitous programming language of the web over the next few years, new frameworks popping up every five minutes and event driven programming taking a lead both ...
32
votes
10answers
5k views

Why aren't there other client-side scripting languages for websites? [closed]

Why is there just support for JavaScript and some VBScript in browsers today? I know JavaScript is good and all, but wouldn't having the option of using another programming language help promote ...
31
votes
14answers
3k views

Is it a common practice to minimize JavaScript usage when building a website?

I've been a web developer for almost 10 years and I've gotten into the habit of trying not to use JavaScript whenever possible. I'm not talking about building web apps here, but database driven ...
31
votes
2answers
2k views

Why does Javascript treat days and months differently?

I've noticed that in JavaScript, when creating a Date, months are zero based, and days aren't. For example: var foo = new Date(2012, 1, 1) produces February 1st 2012 Why is this?
31
votes
3answers
7k views

What does Douglas Crockford mean when he says jQuery doesn't scale? [closed]

In the Q&A section of this talk, Douglas Crockford says that jQuery doesn't scale as well as some other popular libraries. What does he mean by that, and what is it about the other libraries that ...
30
votes
7answers
2k views

Design Patterns for Javascript [duplicate]

A lot of web frameworks have a MVC-style layout to code and approaching problems. What are some good similar paradigms for JavaScript? I'm already using a framework (jQuery) and unobtrusive js, but ...
30
votes
2answers
23k views

Mixing Angular and ASP.NET MVC/Web api?

I come from using ASP.NET MVC/Web API and now I am starting to use Angular but I am not clear on the proper way to mix them. Once I am using Angular does the MVC server side concepts still provide ...
29
votes
4answers
6k views

Does Dart have any useful features for web programmers?

http://www.dartlang.org/ I've checked out the site very briefly, and got curious. Is there any advantages of using Dart? Is it just a replacement for JavaScript? It looks like simpler Java. Writing ...
29
votes
10answers
5k views

Is it worth moving from Microsoft tech to Linux, NodeJS & other open source frameworks to save money for a start-up? [closed]

I am currently getting involved in a startup, I am the only developer involved at the moment, and the other guys are leaving all the tech decisions up to me at the moment. For my day job I work at a ...
29
votes
1answer
106k views

What is the best way to include JavaScript file using script tag?

I generally include JavaScript files using the script tag as below. <script type="text/javascript" src="somefile.js"></script> I have seen some people using the language attribute as ...
29
votes
5answers
1k views

Javascript modularity, server based MVC & business reality

I understand this is a very broad question, but I have worked with various aspects of this problem individually and am struggling to bring all the concepts and technologies together. I'd like to ...
28
votes
8answers
5k views

Is splitting up a function into several inner functions an anti-pattern? [duplicate]

Imagine a long and complicated process, which is started by calling function foo(). There are several consecutive steps in this process, each of them depending on result of the previous step. The ...
28
votes
8answers
10k views

When should JavaScript generate HTML?

I try to generate as little HTML from JavaScript as possible. Instead, I prefer to manipulate existing markup whenever I can and only generate HTML when I need to dynamically insert an element that ...
28
votes
11answers
3k views

Why the recent shift to removing/omitting semicolons from Javascript?

It seems to be fashionable recently to omit semicolons from Javascript. There was a blog post a few years ago emphasising that in Javascript, semicolons are optional and the gist of the post seemed to ...
28
votes
5answers
8k views

Pros and cons of an HTML/JavaScript only web app

I come from an ASP.NET forms background and have found server side coding very powerful in the past. More recently, however, I have been wanting to phase out the server side code of the front-end and ...
27
votes
14answers
8k views

What benefits are there to native JavaScript development? [closed]

Given how much simpler jQuery development is, when compared to native JavaScript, what makes people forgo libraries like jQuery altogether? Is this because jQuery has limitations or it is slow? I ...
27
votes
5answers
2k views

Referencing external javascript vs. hosting my own copy

Say I have a web app that uses jQuery. Is it better practice to host the necessary javascript files on my own servers along with my website files, or to reference them on jQuery's CDN (example: ...
27
votes
6answers
4k views

Dynamic Code Evaluation in Java - Clever or Sloppy?

I am trying to create a flexible ACL framework in Java for my application. Many ACL frameworks are built on a whitelist of rules, where a rule is in the form of owner:action:resource. For example, ...
26
votes
9answers
2k views

Ashamed to admit using jQuery? [closed]

Something I've noticed over the past few weeks is how many big commercial websites use jQuery combined with lots of plugins - but don't admit it. They will rename the main library to something ...
26
votes
6answers
3k views

Tight Coupling Between Javascript, HTML, and CSS: A More Modern Approach?

It's very common to see Javascript bound to certain selectors to find elements, store data, and listen for events. It's also common to see these same selectors used for styling. jQuery (and its ...
26
votes
11answers
4k views

Is javascript worth learning if you do not plan on being a web developer?

I heard Javascript is a full language just like c++. Is this true? What else is it good for programming besides web stuff?
25
votes
14answers
2k views

What shall I include in a 10 week web technologies course? [closed]

In September I will be teaching a university module on web technologies. This session will be available to 1st year (freshman) students who don't necessarily have any programming knowledge or know ...
25
votes
8answers
8k views

The importance of javascript and the best way to learn it? [duplicate]

I'm a new graduate, but I have been doing web development for about six months. When I was finishing university the server side languages (PHP, Java) were more important then client side languages. ...