How to send and receive variables with Javascript?

Hi... first, i have no knowledge of coding javascript. I'm looking for tutorials about just a simple: get a variable from a function in javascript and send a variable using another funcion and i can't find anything that i can understand, so that's my question.

Is there a simple way to call a function to send a variable and another function to get a variable.... (as external interface call in actionscript)? Any sample?

Thanks.