Coffeescript tidbit: try/catch

Really simple, the morale of the story is don’t put your try/catch on one line. Even though the following does compile:

_encodeParam = (str) ->
  try encodeURIComponent(str) catch str

and you would think the catch handler just returns the input str, but the complied code is:

var _encodeParam;
_encodeParam = function(str) {
  try {
    return encodeURIComponent(str);
  } catch (error) {
    str = error;
  }
};

so the magic error variable is actually assigned to string and returned. So coffeescript should return an error (or least a warning) about that compilation, but silently eats your input variable. So, that nice, compact one line of code really needs to be:

_encodeParam = (str) ->
  try
    encodeURIComponent(str)
  catch
    return str

Thanks coffescript.

My real rant is feedback from the compiler. I think a compiler from the ground up needs to think about displaying informational error and warning messages. That why I like the Elm language.