jDays.se presentation

1. Javascript
for multi disciplinary teams
101

2. Francisco M.S. Ferreira
Software Engineer at eBay
I present my own opinion and point of view, not the one of my employer.

3. Why use Java?
•
•
•
•
•
Used everywhere (allegedly)
Strongly typed language
Compiled language
Object Oriented
Tons of available frameworks

4. Why use JavaScript?
•
•
•
•
•
Used everywhere (allegedly)
Strongly typed language
Compiled language
Object Oriented
Tons of available frameworks

5. Why use JavaScript?
•
•
•
•
•
•
Used everywhere (allegedly)
Strongly typed language
Compiled language
Object Oriented
Tons of available frameworks
Extremely flexible

6. Typical team

7. Typical team
Front End
Back End

8. What to expect
• An intro to JavaScript
o Simulate Object-Oriented JavaScript
• Packaging / Folder structure
• Known walls new developers hit
o Type safety
o Single threaded system
o Mountain/Piramid of doom.

9. Java class

10. Flexibility

11. Flexibility

12. My favorite
Fool proof
Private variables
Public functions

13. Tastes like Java

14. Step by step

15. Private variables

16. Public variables

17. Private functions

18. Public functions

19. Static variables

20. Static functions

21. Feels object oriented
No private statics

22. What about extensions?

23. What about extensions?

24. If JS was java…

25. Let’s apply

26. What happened there
• When calling apply or call:
o
o
o
o
The this scope is shared between functions
Allows multiple inheritances
Allows order of execution in inheritances
Directly inherits!

27. What happened there
• When calling apply or call:
o
o
o
o
The this scope is shared between functions
Allows multiple inheritances
Allows order of execution in inheritances
Directly inherits!
• It only shares:
o ‘public’ functions and variables

28. What happened there
• When calling apply or call:
o
o
o
o
The this scope is shared between functions
Allows multiple inheritances
Allows order of execution in inheritances
Directly inherits!
• It only shares:
o ‘public’ functions and variables
• It may overwrite methods or get overwritten

29. Folder naming
Java packages

30. Folder naming
Java packages
JavaScript folders

31. The three big walls of JS
•JavaScript is not type safe!
•JavaScript is single threaded!
•Lot’s of callbacks with closures!

32. Javascript !== TypeSafe
If you use:
===
!==
All these
would be
false

33. Equality of objects is deep
•
Recursively compare all elements
•
If order is guaranteed:
o JSON.stringify && compare JSONs
• Use deep compare function ≈ 120 lines of code
o http://stackoverflow.com/questions/1068834/object-comparison-in-javascript

34. Single Threaded!
setTimeout
someOtherCode
moreCode
...
aCallback

35. Mountain of Doom
• Hard to read
o And maintain
• Callback hell
• Issues
o
o
o
o
Memory Leaks
Error prone
Hard to debug
Hard to test

36. Q&A