But CoffeeScript does introduce new semantics. To name a few: • a classical object model, complete with super() • forced strict equality • loop-local index v

But CoffeeScript does introduce new semantics. To name a few: • a classical object model, complete with super() • forced strict equality • loop-local index variables (gets around the setTimeout(function() {console.log(i)}, 100) problem) • all variables local unless explicitly declared otherwise • CoffeeScript's splat arrays are totally different from JavaScript's arguments object • list comprehensions (whether this is a semantic or syntactic change is debatable, I suppose, but the same could be said for basic OO) • everything is an expression The last one is a biggie that completely changes the meaning of many seemingly identical blocks of code. If that isn't a semantic change, what is?