I'm just moving towards native apps... A friend of mine told me to start with cocos2d, I'm good in javascript. While searching google for cocos2d, and within cocos2d-x.org I found 

 1. cocos2d-x
 2. cocos2d-JSB
 3. cocos2d-html5
 4. cocos2d-Javascript

I know what cocos2d-x is for.. and what cocos2d-html5 is for.. but what is cocos2d-JSB and cocos2d-Javascript..
Can somebody please tell me.. what exactly these 2 things are.. 
My questions are:

 1. Can we develop 100% pure native apps/games in cocos2d-JSB and or cocos2d-javascript. 
 2. I also know cocos2d-JSB is javascript bindings.. but what does that exactly mean?.. 
 3. Last but not least question.. what is cocos2d-Javascript for?.. does that work alone or we need cocos2d-html5 to make it previewable in iOS/Android/WindowsPhone...

Please give me Details.. because i'm so confused... I want to develop native apps for iOS/Android and WindowsPhone.

Thank you