JavaScript – AzureDays

Object JavaScript – Code Walkthrough of a jQuery UI Widget

February 26, 2015

In the last post, Building Stateful jQuery UI Plugin Using Widget Factory, you were introduced to the working structure of jQuery UI Widgets. You learned that it uses the factory pattern is a way to generate different objects with a common interface. And that it Widget Factory adds features to jQuery plug-in.

jQuery UI Widget Factory is under jQuery UI, but you can use it separately for your own widgets. In this post, you will learn the steps you can take to build your own widget. This posts walks through an implementation of the filterable dropdown from Adam J. Sontag’s and Corey Frang’s post: The jQuery UI Widget Factory WAT?

My motivation in this post is to show what goes where when you are designing your widgets. And provide some direction in the steps you can take when building a widget from scratch.

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Object JavaScript – ECMAScript 6 Code Preview

December 17, 2014

ECMAScript 6 specification and implementation is underway and promises to bring many of the features that you’ve learned about in the posts on Object JavaScript.

This post gives you an idea of what the code looks like in ECMAScript 6. This post doesn’t cover ever feature. But you will learn about how ECMAScript 6 relates to:

Scope
Arrow Functions and Lexical this
Default Function Parameters
Classes
Inheritance
Modules
for-of
Arrow functions
Promises

I won’t come close to covering all the features. But you can get an idea of how ECMAScript 6 works to support the idea of Object JavaScript. Look to the references and to the specification for information about: Parameter handling, multiple return values, collections, destructuring, rest parameters & spread operator, iterators, array comprehension, and more.

Special thanks to Axel Rauschmayer for many of the snippets.

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Object JavaScript – ECMAScript 6 Futures Overview

December 15, 2014

ECMAScript 6 specification and implementation is underway and promises to bring many of the features that you’ve learned about in the posts on Object JavaScript . ECMAScript is the foundation of JavaScript. ECMAScript has gone through several versions. The current browsers support ECMA Script 5. . The discussions today are revolving improvements beyond versions past 5, which are code-named, ECMAScript Harmony.

The ES6 compatibility table is very useful, as it tells us the ES6 features that are supported in the current browser. It also gives us a handy link to the specifications for each of the features listed. You will find that the current versions of browsers are implementing these features as fast as they can. The table shows that some subset of the feature exists, so as we say, “your mileage may vary”. That said, it is coming.

I don’t have any particular insider information, but wanted to share what I am learning as I explore ECMAScript 6 and what it means to the way that code is written today. In my search I found two great articles that I am pulling information from:

Use ECMAScript 6 Today
Slide Deck: ECMAScript 6: what’s next for JavaScript? (August 2014)

My value add is to provide context for the previous posts and show how your code in the future could look like to implement many of the same features. And this topic is fluid so again, “your mileage may vary”. My intent is to give you can idea of what is coming and how soon to help you decide how deeply you want to invest in the current technologies. That said, one of the goals in ECMAScript 6 is to not break anything you are doing now.

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Snippet – Checking Internet Connection, No More Hanging App

July 22, 2014

When you are writing your single page application (SPA) may find that you need to check your connection. The idea is that you might have one set of logic for your connected app and another for when you are disconnected.

In previous posts, AppCache for Offline Apps and Loading, Caching LoDash or Underscore Templates Using RequireJS, AppCache, you learned that your Web app did not have to be online to be run. In fact, when building HTML apps for mobile devices, you are running without a connection.

So how do you check? How do you know when you can upload and download new information from the Web?

Many of the comments on StackOverflow have to do with the connection hanging. The following snippets help you work around the issue.

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Snippets – Filtering JSON Using jQuery Grep, Filter, Map

July 13, 2014

When you have a JSON array, you may want to get one or more items from the array and display. jQuery offers two functions that can help: grep and filter.

$.grep(). Finds the elements of an array which satisfy a filter function. The original array is not affected.
$filter(). Reduce the set of matched elements to those that match the selector or pass the function’s test.
$.map(). applies a function to each item in the array, thus returning a modified array

In other words, $.grep() removes items from an array as necessary so that all remaining items pass a provided test; .filter() constructs a new jQuery object from a subset of the matching elements.

Also, filter is intended to be used with html elements, and that is why it is a chainable function that returns a jQuery object and it accepts filters like “:even”, “:odd” or “:visible” etc. You can’t do that with the grep function, which is intended to be a utility function for arrays.

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Single Page App – isLoading jQuery Plugin to Indicate Content Loads

July 12, 2014

When you’re loading information using jQuery AJAX, you may want to provide visual feedback when loading data or for any action that would take time.

In this Snippet, you will learn how to:

Load JSON data from a getJSON call to our server.
Show and hide a spinning indicator inside a div.
Bind the incoming data to a view model object.
Use the view model to populate an external template.

Then once the page is loaded, it will display the data based on an external template.

And we’ll provide some tips on how you you can use the IsLoading library to display the loading indicator on top of the page while loading and on top of the div itself.

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Snippet – C#, JavaScript, jQuery, Underscore ForEach Loops

July 11, 2014

The foreach statement repeats a group of embedded statements for each element in an array or an object collection. The foreach statement is used to iterate through the collection to get the information that you want.

It is not be used to add or remove items from the source collection to avoid unpredictable side effects. (If you need to add or remove items from the source collection, use a for loop.)

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Single Page Apps – Retrieving, Caching Server Requests Using AmplifyJS

June 5, 2014

You may want to use storage to store data. You can save the data your user has entered in a wizard. Or you might want to save data so you can provide an offline experience. Or you may want to store user preferences. Local storage is a good idea anytime you do not want, or need your user or your application to start all over.

AmplifyJS is a very neat library that provides a consistent API to handle client storage that works in most browsers.

In this post, you will learn to retrieve the data through amplify.request without concern for data caching, server interface, resource location, data types, wrappers, and all the other specificities of the client/server interaction.

Requests made through amplify.request will always be resolved asynchronously, even if the resource invokes the callbacks immediately.

You will probably need jQuery for Amplify Request. The default request type shipped with AmplifyJS does utilize jQuery AJAX, but you can just as easily create a new request type that uses Dojo, MooTools, etc.

However the publish/subscribe and store components do not use jQuery at all.

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Single Page Apps – Store Your Data Locally in Knockout Using AmplifyJS

June 2, 2014

Amplify store and Knockout can be great partners. For example, you can use client storage to improve user experience, remembering user preferences or previously entered values such that the user doesn’t have to start all over.

There is a tutorial on Knockout that provides for client storage. In the tutorial, Knockout uses Amplify to restore user data when the user revisits the site.

You can augment Knockout observables with additional functionality, by using extenders.

You can use extender to automatically store and restore any observable property. Continue reading “Single Page Apps – Store Your Data Locally in Knockout Using AmplifyJS”

Single Page Apps – Local Data Store with AmplifyJS

June 1, 2014

AmplifyJS is a very neat library that provides a consistent API to handle client storage that works in most browsers.

Of course, you can use HTML5 Local Storage. But amplify.store supports IE 5+, Firefox 2+, Safari 4+, Chrome, Opera 10.5+, iPhone 2+, Android 2+ and provides a consistent API to handle storage cross-browser.

Note: Because of the JSON dependency, you need to add json2.js for support in browsers without native JSON support, including IE 5, IE 6, IE 7, Firefox 2.0 and Firefox 3.0.

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