"global" works in scripts as well. On the other hand, scripts use the current workspace instead of creating their own, so if you have one script call another, or run two scripts after each other, then they will have access to all of each other's variables.
To have the function be able to access a variable from the script that called it, you can use evalin('caller'). This is not recommended, though: it is better for the value of the variable to be passed in the call to the function.
