How would you greet/meet someone casually in Japanese?

[BeckyLilac]

For example, instead of the "Hello. How are you doing?" that's often the example in learn English textbooks, most people would just be like "Hey, Wassup?" or something like that.

Is there such a case in Japanese? Is so, how would you greet someone casually?

 

[Rawre]

formally, Konnichiwa o genki desuka?
Hello, how are you doing?

friends (not that close), Konnichiwa genki?
Hello, you doing good?

friends(close)#1, Yo! Genki?
Yo! Doing good?

friends(close)#2, Chiis genki ka? (it's very slangy)
Hey, ya doin good?