If you just want to know about the parameters for a function it is either Scripting Index or JSL Syntax Reference. And I start with Scripting Index. If it doesn't have enough information I will try Topic Help button from there. It will then (hopefully) take me to JSL Syntax Reference or Scripting Guide.
For example Contains(), starting from Scripting Index
I end up in JSL Syntax Reference page
And it has few extra links which might be helpful to see additional examples.
-Jarmo