This is a deliberate design decision in CoffeeScript – &quot;everything is an expression&quot; (see <a href="http:&#x2F;&#x2F;coffeescript.org&#x2F;#expressions" rel="nofollow">http:&#x2F;&#x2F;coffeescript.org&#x2F;#expressions</a>).<p>This is probably as a result of CoffeeScript&#x27;s Ruby-esque syntax and semantics. It does mean you can write some very clear and succinct code at times, but the tradeoff is that it can have unforeseen performance implications.