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EXTJS4 FAQ

  
EXTJS development:

- how to use MVC?
- what are EXTJS MVC advantages?
- how to customize componentst?
 - How to implement themes?

- How to implement/show multiple views on single screen without using server side template logic like jsp, velocity, handlebars?
- explain Ext component life cycle?
- explain event handling in extjs?
- can we develop application with using Extjs mvc architecture?
- explain javascript closure?
- what are scopes in javascript?
- difference between ext 3 and ext 4 versions?
- do javascript have classes?
- how to declare a class in javascript? how many ways javascript function can be defined?
- what is event bubbling in javascript?

- Difference between Ext.create() and  Ext.extend classes?
- how to define a own ext class?
- what is xtype?
- Ways to define a Javascript class?
- html5 supported older browsers?
- what is new with css3?
- when to use prototype?
- how to write object javascript?

MVC best practices:

 1.What is criteria for having more than one controller. What factors decide multiple controllers.
2.Is it good practices to get reference to controller using Ext.getController() method when controller reference is not available using "this". If not, How to avoid this.
3.What is best way to have global application level variables.
4.How acceptable is it to add custom properties to component object itself to avoid having long list refs or global variables.
5.Is there any sencha recommended way to simplify async method calling which makes code readable.

 Answered:
1.
This is part of the app structure that you have to decide, there isn't a one-size-fits-all answer. I usually split up my app into features and have a controller per feature. Like an email app would have an address book feature so it would have a controller where the email portion is another. However the email portion may be too large for a single controller so you may have to split it up more. Also, I like to have my navigation stuff in one controller, just is more organized for me.
2.
Usually you shouldn't need to do cross-controller calls but there are times where you may have to for code reusability or what not. I tend to always have a utility app that has my code that I use a lot but that can get a little unorganized so it kind of depends on how your app shakes out.
3.
This goes with my #2 where I have a utility class to hold configs or global variables. I don't like to pollute my Ext.application or app namespace with variables too much.
4.
Very much acceptable. For instance I give my buttons a custom 'action' property to resolve one button against another. So then I can have a ComponentQuery like: 'formpanel button[action=SaveUser]'
 5.
 I'm not too sure what you mean by this. Like you have a method that you need to execute some callback method at some point? I would just have a callback argument and execute it when I need to.


References:
http://www.phpied.com/3-ways-to-define-a-javascript-class/
http://www.javascriptkit.com/javatutors/oopjs.shtml#.UkremtLktyw
http://javascript.crockford.com/survey.html
http://javascript.info/tutorial/bubbling-and-capturing
http://www.codecademy.com/tracks/javascript


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