wintellect - devscovery - enterprise javascript development 2 of 2

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Enterprise JavaScript Development: Oxymoron?Part 2 of 2

Jeremy Likness (@JeremyLikness)Principal Consultantjlikness@wintellect.com Copyright © 2012

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Agenda• JSLint / JSHint – personal style is for fashion, not code• jQuery – one API to bind them all• JSON and Web API – flexible information on demand• Twitter Bootstrap – one layout to rule them all• Underscore.js – the Swiss army knife of JavaScript • Backbone.js – MVC on the client • RequireJS – dependency resolution• MVVM (for example, Kendo UI) – “Gotta keep ‘em separated”• Amplify.js – publisher/subscriber for the client• … and many more great projects we won’t have time to

discuss today

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JSLint / JSHint• JSLint – JavaScript code that checks for problems in JavaScript

code• Authored by Douglas Crockford, who helped develop the

JavaScript language, pioneered JSON and wrote The Good Parts

• Very restrictive – many debates over whether it is the right tool or not

• JSHint – code quality tool, open source project– Fork of JSLint– More flexible– Help avoid typos and language “gotchas”

• Available as a Visual Studio extension– Install from Tools -> Extensions and Updates– Configure – you can even error builds based on the results– Start early because existing code can be a bear to fix

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JSLint and JSHint

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jQuery• Very “recent” API – released in 2006 • Most popular JavaScript library in use• Designed to make it easier to perform client-side scripting

without worrying about browser-specific idioms• Bundled with the Visual Studio 2012 MVC templates• Support for current Firefox, Safari, Opera, and Chrome

versions, and Internet Explorer 6 and above• Support for plug-ins

– jQuery UI– jQuery grid– jQuery mobile

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jQuery

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JSON and Web API• JSON is client-side data “for free” • JSON is very human readable • JSON is more compact than XML • JSON is a popular format for REST • Web API makes it extremely easy to stand up REST end points • Web API provides true “negotiation” of content types • Web API gives control over response codes • Very easy syntax with jQuery

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JSON and Web API

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Twitter Bootstrap• Fixed and fluid layouts• Browser compatibility• Tablet and smartphone support (responsive CSS)• Provides tons of CSS for existing components:

– Forms– Labels– Alert boxes– Typographical sections

• Also includes JavaScript extensions for various features– Alert, Tooltip, Modal, etc.

• Great way to baseline your application• Completely customizable CSS

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Twitter Bootstrap

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Underscore.js• Swiss Army Knife• Lots of great collection-based functions

– Each– Find– Filter– Map– Reduce– Pluck

• Testers – Is Empty?– Has?– Etc.

• Templates• Helpers i.e. bind = no more self-invoking function

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Underscore.js

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Backbone.js• MVC on the client (C = Collection, not Controller!)• Models

– Constructors– Defaults– Change notification– Initialization

• Collections– Auto-binding to REST end points – Change notification

• Views– Bind to tags – Support for templates

• Events• Navigation / Browser journal• Great for “data over forms” style applications

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Backbone.js

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Require.js• Script file / module loader• In-browser dynamic assembly of components • Designed to improve speed and quality• Load modules only if/when/as needed• Optimizer tool can compress JavaScript into single file • In each file, you use this to load other scripts that are

dependencies:require(["app/services"], function(services) { ...

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Require.js

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MVVM (Kendo UI)• Telerik• Knockout.js equivalent “open source” version• ObservableObject

– Bind for event handlers– Get/Set for property updates with change notification– toJSON for clean transport– Exposes a change event

• ObservableArray – Array with change tracking– Most basic array functions supported

• Model – specialized ObservableObject with data definition for data sources

• Validator – works with existing HTML5 tags and allows for custom rules

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Kendo UI / MVVM

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Amplify.js (Postal.js)• JavaScript implementation of publish/subscribe pattern• Synchronous and asynchronous • No external dependencies • Channels for further scoping• Envelopes for correlation, tracking, etc.• Use events on objects and subscribe within modules• Use publisher/subscriber for decoupled communication

between/across modules • Use the adapter pattern to adapt pub/sub to events • Wiretap to log all events

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Amplify.js

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Recap• JavaScript is good • JavaScript has bad parts• JavaScript can get ugly• Known the language• Program with JavaScript, not "C# using JavaScript"• Learn how to make your code:

– Use the good parts (JSHint/JSLint)– Cross-browser friendly (jQuery)– Fluid and adaptable (Twitter Bootstrap)– Data-friendly (JSON)– Consistent (tools like underscore)– Modular (Backbone, Requires) – Testable and Extendable (MVVM)– Decoupled (Postal)

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Links and Recommendations

• Twitter me: @JeremyLikness

• Blog me: http://csharperimage.jeremylikness.com/

• JavaScript: The Good PartsISBN: 0596517742

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Questions?

consulting training design debugging

Jeremy Likness (@JeremyLikness)Principal Consultantjlikness@wintellect.com