Category Archives: JavaScript

MathJax – beautiful math in all browsers

Having come across this and having the regular need to represent complex math in web… I was happy to be introduced to MatchJax….

MathJax is an open source JavaScript display engine for mathematics that works in all modern browsers.

This means no more setup for readers. No more browser plugins. No more font installations… It just plain works.

MathJax

 

 

 

It’s the most elegant way currently available to include math in your markup… check it out…
http://www.mathjax.org/

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JQPLOT – A Versatile and Expandable jQuery Plotting Plugin

jqPlot is a plotting and charting plugin for the jQuery Javascript framework.

Image

jqPlot produces beautiful line, bar and pie charts with many features:

  • Numerous chart style options.
  • Date axes with customizable formatting.
  • Up to 9 Y axes.
  • Rotated axis text.
  • Automatic trend line computation.
  • Tooltips and data point highlighting.
  • Sensible defaults for ease of use.

jqPlot is an open source project by Chris Leonello

Check it out…
http://www.jqplot.com/

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FLOT – Attractive JavaScript plotting for jQuery

Flot is a pure JavaScript plotting library for jQuery, with a focus on simple usage, attractive looks and interactive features.

FlotCharts Homepage

Who’s behind this?

Flot is the combined result of countless suggestions, patches and bug reports by the people using Flot.
It was started by Ole Laursen, sponsored by IOLA, an agile little Danish web-development house with a keen eye for Python/Django and jQuery. If you need commercial support, you’re welcome to contact us – read more here.
It is currently being maintained by David Schnur.

Check it out…
http://www.flotcharts.org/

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AngularJS Directive… preloader experiment

I’m still a newbie to AngularJS development, however I have to admit that I’m having a lot of fun thinking of new directives and exploring increasingly better ways to implement them, mostly inspired by the lively and vital AngularJS community.

I’m posting one of my most recent experiments which was to have a very simple way to add preloading functionality to an AngularJS application… and this i what I came up with.

Please note that this is purely experimental and the reason for me posting it is to allow others to start thinking of their own directives as well as learn something in the process..

Now… one of my objectives was that I wanted to be able to point to an external file for the preloader content, however the preloader content should also be able to contain AngularJS itself.

This lead me to the use of the AngularJS-native “include” directive and the “$compile” service.

The actual implementation of the loading was out of scope for this small experiment, so I decided to fake it with a simple timer using the relatively new “$timeout” service, which recently replaced the “$defer” service as a way of postponing function calls.

Furthermore, since basically every application I build contains some level of DOM manipulation, I have no problem with having jQuery as a pre-requisite, so the implementation is using jQuery for the DOM manipulation, however it would be trivial to remove or replace this requirement.

AngularJS Community Member, Glen Maddern, has been so kind to post my experiment as a executing sample in the form of a Gist on GitHub:
http://2886724.run-a-gist.herokuapp.com/

The contents of the splash.html is very crude for this example, however it could be any HTML content…

<h1 ng-click="clickHandler(event)" ng-controller="PreloaderController">
	Loading, please wait...still loading {{percentCompleted}}%
</h1>

As you can see in the the snippet above, the preloader HTML is driven by a PreloaderController… and it has a clickHandler for demo purposes to shurtcut the preloading…

function PreloaderController( $scope, $timeout ) {

	$scope.percentCompleted = 0;

	$scope.applicationProgressMock = function() {

		if( $scope.percentCompleted == 100 ) {
			$scope.$emit( "applicationComplete" );
		}
		else
		{
			$scope.percentCompleted += 5;
			$timeout( $scope.applicationProgressMock, 100 );
		}
	}
	$timeout( $scope.applicationProgressMock, 100 );

	$scope.clickHandler = function( event ) {
		$scope.percentCompleted = 100;
	}
}

The directive itself is fairly simple and straightforward JavaScript…

PreloaderFactory = function( $compile ) {

	var directive = {

		restrict : "A",

		link : function( scope, elm, attrs ) {

			scope.preloader = jQuery( "<ng-include />" );
			scope.preloader.attr( "src", "'"+ attrs.preloader +".html'" );

			$compile( scope.preloader )( scope );

			jQuery( "body" ).append( scope.preloader );

			scope.$on( "applicationComplete", function( event ) {

				jQuery( scope.preloader ).remove();
			});
		}
	}
	return directive;
}

Now, my main HTML looks like this, pretty advanced app…

<html ng-app="application" preloader="splash">
  <head>
    
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    
    <title>Preloader Experiment</title>
    
    <script src="http://code.angularjs.org/angular-1.0.0rc10.min.js"></script>
    <script src="http://code.jquery.com/jquery-1.7.2.min.js"></script>
    <script src="preloader-0.0.1.js"></script>
    
    <script>
    
    	angular.module( "application", [] )
    	
    	.directive( "preloader", PreloaderFactory );
    	
    </script>
    
  </head>
  <body>
  
  </body>
</html>

That’s it, a faily simple and crude implementation of a preloader tag… comments are much appreciated, however please note that this was purely intended as an inspiration and not a cookbook recipe…

In any case I decided to put it on GitHub… I sincerely hope to be able to get much more samples up there and that they will increase in quality…
https://github.com/pmoelgaard/labs/tree/master/angular/preloader-directive

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AppJS… Build Cross-Platform Applications

…for desktop using HTML, CSS, Javascript !

It’s still very early stuff, however its interesting to see how a lightweight container like this may develop into something pretty useful, at least the stack of technologies used is entirely aligned with how I would set out to build a lightweight app container…

Why AppJS?

Because it is simple and yet powerful. Using AppJS you don’t need to be worry about coding cross-platform or learning new languages and tools. You are already familiar with HTML, CSS and Javascript. What is better than this stack for application development? Beside, AppJS uses Chromium at the core so you get latest HTML 5 APIs working. So relax and focus on the task your application should do.

HTML 5

AppJS allows you to use HTML 5 APIs to create attractive applications from Word Processors to 3D Games. You are no longer limited to default GUI widgets that plaforms force you to use. Creating custom UIs is now only limited to your imagination!

CSS 3

Using CSS you can decorate widgets as you like. Create a custom widget in HTML and complete your work with decorating it. Adding shadows, animating elements and transforming objects in 3D space are a few examples of what you can do with CSS 3.

Node.js

The interesting part of AppJS is that it uses Node.js as the backbone. Node.js has been built to ease the process of developing scalable network applications. But today, you can see Node nearly everywhere! It has a nice API and lots of modules.

Check it out…
http://appjs.org/

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FixieJS… a tremendously cool html utility

Fixie.js is an open source tool that automatically adds filler content to HTML documents.

Image

Adding lorem ipsum text to HTML documents involves copy-pasting, manual editing, and increasingly unwieldy code.

By interpreting your semantic HTML5 tags, Fixie will automagically add the right type of content in the right places. Headings, paragraphs, links, images, sections… trust me, it’s all there. That way you can focus on your design, instead of finding the right filler content.

A nice example on how this can be useful can be found in the equally clever utility: FlickHoldr
http://flickholdr.com/

Image

FlickHoldr simply gets placeholders related to the site you are developing, by pulling images from flickr based on tags… very simple and elegant…

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AngularJS… a selection-change directive… an early implementation

having run into some issue implementing a change handler on the select control without setting the model property… I decided to see how it could be to implement a selectionHandler directive…

I started out with this implementation which obviously is far from best practice and far from ideal yet… next step will be to find the best practice to implement a tag for an entire “combobox”…

HTML

<select ng-datasource="candidateContacts" ng-selection-change="selectContact">
	<option ng-repeat="candidateContact in candidateContacts" ng-selected="candidateContact.id == contact.item.id">
		{{candidateContact.name}}
	</option>
</select>

JavaScript

.directive( "ngSelectionChange", function( $compile ) {
		return function( $scope, $element, $attrs ) {

			jQuery( $element ).change( function( e ) {

				var target = jQuery( e.target );

				var datasourceKey = target.attr( "ng-datasource" );
				var datasource = $scope.$eval( datasourceKey);

				var actionKey = target.attr( "ng-selection-change" );
				var action = $scope.$eval( actionKey );

				var selectedIndex = target.prop( "selectedIndex" );
				var selectedItem = datasource[ selectedIndex ];

				action.call( $scope, selectedItem );
			});
		}
	})

UPDATE
I just stumbled upon the concept of using accessor’s in the directive scopes, that will help me get rid of the redundancy in the declaration of the datasource/iterator…
http://jsfiddle.net/ADukg/10/

UPDATE
I came across this directive when browsing the recently updated documentation system, this will do fine so there is no need to implement a ComboBox since the functionality is covered by the native select directive… http://docs.angularjs.org/api/angular.module.ng.$compileProvider.directive.select

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StateMachines in JavaScript… on the path to programmable workflows

In the need for a Sequential Workflow for JavaScript applications, I was lucky to find a great StateMachine implementation of a Finite StateMachine…

Unfortunately, I wasn’t really looking for a Finite StateMachine, but more of a Sequential Workflow that I can use to drive an application consisting of a distinct set of actions in a predictable order… Anyways…

Jakes Gordon has gone the effort of implementing a swift and cleverly designed finite statemachine and made it available on GitHub… its entirely standalone and has no dependencies on other frameworks or libraries.

If you are familiar with using finite statemachines, it will come easy to use the library, otherwise Jakes has formulated a well articulated and easily-understandable ReadMe…

https://github.com/jakesgordon/javascript-state-machine/#readme

Jakes has documented the library well, and is providing a great example on how to use it in a graphical way…
Image
http://codeincomplete.com/posts/2011/8/19/javascript_state_machine_v2/example/

Anyways, check out the library if you are in need of a finite statemachine for your JavaScript applications…

https://github.com/jakesgordon/javascript-state-machine/

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Using Angular with jQuery

When familiarizing oneself with AngularJS, its on some occasions a forthcoming thought if this is all you need since they do exclude each other in many ways, however they have been build with two very different perspectives on application design… jQuery is basically a library focused on DOM querying and manipulation, AngularJS is an application framework and micro-architecture…

That they however are not entirely mutually exclusive becomes evident when diving in to the angular.element method… as it turns out Angular is actually using jQuery (or of jQuery is not loaded, an embedded version referred to as jqLite).

angular.element wraps a raw DOM element or HTML string as a jQuery element. angular.element can be either an alias for jQuery function, if jQuery is available, or a function that wraps the element or string in Angular’s jQuery lite implementation (commonly referred to as jqLite).

Real jQuery always takes precedence over jqLite, provided it was loaded before DOMContentLoaded event fired.

jqLite is a tiny, API-compatible subset of jQuery that allows Angular to manipulate the DOM. jqLite implements only the most commonly needed functionality within a very small footprint, so only a subset of the jQuery API – methods, arguments and invocation styles – are supported.

Note: All element references in Angular are always wrapped with jQuery or jqLite; they are never raw DOM references.

So, if you are using Angular as your application framework and you see a need to use jQuery for one or more of the many things jQuery is absolutely amazing and almost second to none, then don’t hesitate to do so, they are both great system citizens and work great as peers in your applications…

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AngularJS… by Google

AngularJS is by far one of the most promising frameworks to fill the gap of JavaScript development in the RIA developer’s toolbox…. so regardless of me posting about it before, I felt compelled to do it again…

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The übercool thing about AngularJS is that its entirely unobtrusive and an excellent system citizen, it works perfectly fine together with any other framework you may depend on…

Brackets is build using jQuery, so targeting technology agnosticism when choosing an application framework is empiric… enter AngularJS.

Comparing to KnockoutJS and BackboneJS; AngularJS is definitely comparable in features and the coding elegance is by far higher than with either of the aforementioned…

Check it out (again)…
http://angularjs.org

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