WebGl and WebJavaScript

hi!

i have read this link webGl unity i m making WebGl project in unity where user have to upload a file , but unity does not provide any file piker, so i decide to go with javascript (web).

i m stuck and could not make jslib because i dont find any document, can you plz provide any thing ..? is there way to make variables in jslib..?

2nd can we use simple javaScript as jslib ,