34 posts tagged with "javascript"

I love jQuery Validation. I was recently putting together a screen which had a lot of different bits of validation going on. And the default jQuery Validation approach of displaying the validation messages next to the element being validated wasn't working for me. That is to say, because of the amount of elements on the form, the appearance of validation messages was really making a mess of the presentation. So what to do?

The modern web is JavaScript. There's no two ways about it. HTML 5 has new CSS, new HTML but the most important aspect of it from an application development point of view is JavaScript. It's the engine. Without it HTML 5 wouldn't be the exciting application platform that it is. Half the posts on Hacker News would vanish.

OK the title of this post is a little verbose. I've just wasted a morning of my life trying to discover what happened to my ability to debug JavaScript in Visual Studio 2012. If you don't want to experience the same pain then read on...

Last time I wrote about marrying up Twitter.Bootstrap.MVC4 and Bootstrap Datepicker. It came together quite nicely but when I took a more in depth look at what I'd done I discovered a problem. The brief work on regionalisation / internationalisation / localisation / globalisation / whatever it's called this week... wasn't really working. We had problems with the validation.

Updated 14/01/2013​

Since I wrote this I've taken things on a little further - to read about that go here.

I have occasionally done some server-side JavaScript with Rhino and Node.js but this is the exception rather than the rule. Like most folk at the moment, almost all the JavaScript I write is in a web context.

I wanted to write about a JavaScript library which seems to have had very little attention so far. And that surprises me as it's

I've so named this blog post because it shamelessly borrows from the fine work of others: Sebastian Markbåge and Nathan Vonnahme. Sebastian wrote a blog post documenting a good solution to the ASP.NET JavaScriptSerializer DateTime problem at the tail end of last year. However, his solution didn't get me 100% of the way there when I tried to use it because of a need to support IE 8 which lead me to use Nathan Vonnahme's ISO 8601 JavaScript Date parser. I thought it was worth documenting this, hence this post, but just so I'm clear; the hard work here was done by Sebastian Markbåge and Nathan Vonnahme and not me. Consider me just a curator in this case. The original blog posts that I am drawing upon can be found here: 1. http://blog.calyptus.eu/seb/2011/12/custom-datetime-json-serialization/ and here: 2. http://n8v.enteuxis.org/2010/12/parsing-iso-8601-dates-in-javascript/

As I've started making greater use of JavaScript to give a richer GUI experience the amount of JS in my ASP.NET apps has unsurprisingly ballooned. If I'm honest, I hadn't given much consideration to the code quality of my JavaScript in the past. However, if I was going to make increasing use of it (and given the way the web is going at the moment I'd say that's a given) I didn't think this was tenable position to maintain. A friend of mine works for Coverity which is a company that provides tools for analysing code quality. I understand, from conversations with him, that their tools provide static analysis for compiled languages such as C++ / C# / Java etc. I was looking for something similar for JavaScript. Like many, I have read and loved Douglas Crockford's "JavaScript: The Good Parts"; it is by some margin the most useful and interesting software related book I have read.So I was aware that Crockford had come up with his own JavaScript code quality tool called JSLint. JSLint is quite striking when you first encounter it:

Yes the title of this post is *painfully* verbose. Sorry about that. Couple of questions for you: - Have you ever liked the way you can have base classes in C# which can then be inherited and subclassed in a different file / class

Update​

The speed of change makes fools of us all. Since I originally wrote this post all of 3 weeks ago Visual Studio 11 beta has been released and the issues I was seeking to solve have pretty much been resolved by the new innovations found therein. It's nicely detailed in @carlbergenhem's blog post: My Top 5 Visual Studio 11 Designer Improvements for ASP.NET 4.5 Development. I've left the post in place below but much of what I said (particularly with regard to Hungarian Notation) I've now moved away from. That was originally my intention anyway so that's no bad thing. The one HN artefact that I've held onto is using "$" as a prefix for jQuery objects. I think that still makes sense. I would have written my first line of JavaScript in probably 2000. It probably looked something like this: alert('hello world'). I know. Classy. As I've mentioned before it was around 2010 before I took JavaScript in any way seriously. Certainly it was then when I started to actively learn the language. Because up until this point I'd been studiously avoiding writing any JavaScript at all I'd never really given thought to forms and conventions. When I wrote any JavaScript I just used the same style and approaches as I used in my main development language (of C#). By and large I have been following the .net naming conventions which are ably explained by Pete Brown here. Over time I have started to move away from this approach. Without a deliberate intention to do so I have found myself adopting a different style for my JavaScript code as compared with anything else I write. I wouldn't go so far as to say I'm completely happy with the style I'm currently using. But I find it more helpful than not and thought it might be worth talking about. It was really 2 things that started me down the road of "rolling my own" convention: dynamic typing and the lack of safety nets. Let's take each in turn....

So back to JSON. For those of you that don't know JSON stands for JavaScript Object Notation and is lightweight text based data interchange format. Rather than quote other people verbatim you can find thorough explanations of JSON here: - Introducing JSON

This post originally started out as an explanation of JSON. However as I wrote this quickly got abandoned in favour of writing about how I came to use JSON in the first place - which was through the use of Ajax. Having written a goodly amount I've now decided to move the actual JSON stuff into another post since I think Ajax is probably worth thinking about by itself rather than as an aside. So let me start at the beginning and explain how I came to use Ajax in the first place (this may take some time so please bear with me). In late 2004 I first started working on a project which I was to remain involved with (on and off) for a very long time indeed. The project was part financial reporting system and part sales incentivisation tool; it was used internally in the investment bank in which I was working. The project had been in existence for a number of years and had a web front end which at that point would been built in a combination of HTML, JavaScript, classic ASP and with a Visual Basic 6.0 back end. One of the reasons I had been brought on to the project was to help ".Net-ify" the thing and migrate it to ASP.NET and C#. I digress. The interesting thing about this app was that there were actually some quite advanced things being done with it (despite the classic ASP / VB). The users could enter trades into the system which represented actual trades that had been entered into a trading system elsewhere in the organisation. These trades would be assigned a reporting value which would be based on their various attributes. (Stay with me people this will get more interesting I *promise*.) The calculation of the reporting value was quite an in depth process and needed to be performed server-side. However, the users had decreed that it wasn't acceptable to do a full postback to the server to perform this calculation; they wanted it done "on-the-fly". Now if you asked me at the time I'd have said "can't be done". Fortunately the other people working on the project then weren't nearly so defeatist. Instead they went away and found Microsoft's webservice.htc library. For those of you that don't know this was a JavaScript library that Microsoft came up with to enable the access of Web Services on the client. Given that it was designed to work with IE 5 I suspect it was created between 1999-2001 (but I'm not certain about that). Now it came as a revelation to me but this was a JavaScript library that talked to our web services through the medium of XML. In short it was my first encounter with anything remotely Ajax-y. It was exciting! However, the possibilities of what we could do didn't actually become apparent to me for some years. It's worth saying that the way we were using webservice.htc was exceedingly simplistic and rather than investigating further I took the limited ways we were using it as indications of the limitations of Ajax and / or webservice.htc. So for a long time I thought the following: - The only way to pass multiple arguments to a web service was to package up arguments into a single string with delimiters which you could split and unpackage as your first step on the server.

So it's 2010 and I've started using jQuery. jQuery is a JavaScript library. This means that I'm writing JavaScript... Gulp! I should say that at this point in time I hated JavaScript (I have mentioned this previously). But what I know now is that I barely understood the language at all. All the JavaScript I knew was the result of copying and pasting after I'd hit "view source". I don't feel too bad about this - not because my ignorance was laudable but because I certainly wasn't alone in this. It seems that up until recently hardly anyone knew anything about JavaScript. It puzzles me now that I thought this was okay. I suppose like many people I didn't think JavaScript was capable of much and hence felt time spent researching it would be wasted. Just to illustrate where I was then, here is 2009 John's idea of some pretty "advanced" JavaScript: