Coffeescript to javascript transpiling Inaccuracy

Coffeescript to javascript transpiling Inaccuracy

I don't know if this is IDE related, or purely about the transpiling
process. I use Webstorm on a mac, and have node,npm and coffeescript
installed. The IDE is using that to make the transpiling to javascript:
//Coffeescript code, simple variable declaration
myamount = 56
//Traspiled javascript code
(function() {
var myamount;
myamount = 5;
}).call(this);
Any clue why it puts the variable in anonymous function ? This is not
correct transpiling.