Question

I am trying to add a method to the String primitive type/class where I can extra params from a URL string

String::getUrlParams = ->                        # line 1 
    false unless ( params = @.split('?')[1] )    # line 2
    # ...

In Chrome console, when I deliberately call this method with a string of URL without params, I expect it to just return false.

"http://dns.com/".getUrlParams();

but it goes pass through line 2.

if I change line 2 to

   return false unless ( params = @.split('?')[1] ) # line 2`

then it does return false and stops the function at line 2

Any idea why coffeescript isn’t returning false and halts the function in the first version?

Thank you

Answer 1

Coffeescript returns only the last function statement. If something follows some statement, that you want to return in middle of function, then you should do that explicitly.

–Short thoughts–
In short – Coffeescript compiler is not that smart, to predict, where you may want or may not want to return something. And same applies to most compilers now days. Also it’s non-smartiness avoids most of mistakes, which would be caused because of premature return.