It removes the brackets and the return keyword, const is in fact a constant but this not ES6 it is just doing a function expression instead a function declaration (you create a const variable and assign an anonymous function to it instead of using the keyword 'function')
This is used for readability and to avoid hoisting that can be confusing.
Given that brackets and the return keyword (and the function keyword!) are core parts of functions (a scope and a value to return to the caller), I would argue that removing these key parts of a function makes it harder for someone not familiar with ES6 to see that it is a function.
This reminds me of Ruby's return-the-last-evaluated-thing-in-a-function semantics (which sadly Rust copied). Having to type one extra word is not such a burden that you should add cognitive overhead each time someone not intimately familiar with the language has to read your code.
If the argument is that only ES6 experts should only ever have to read or write ES6 code, then I would argue that any syntax argument is pointless because only experts can comment on a languages syntax -- and thus COBOL objectively has the best syntax and you cannot disagree unless you are a COBOL expert.
It does seem strange if you think of it as “return the last evaluated thing from the function.” But that’s not the semantic; the semantic is “everything is an expression and expressions evaluate to a value.” Removing this behavior would make these languages less consistent.
(And yes, in both Ruby and Rust not literally everything is an expression, but almost everything is.)
I agree that because of common uses of things like match in Rust it makes it consistent to also do it for functions. I don't agree that the reason why it's consistent is because a function body is an expression (though of course you have more expertise than me on this one -- and Rust does actually treat scopes much more strictly than most other languages so you could argue every scope has the smell of a function call associated with it).
> This reminds me of Ruby's return-the-last-evaluated-thing-in-a-function semantics (which sadly Rust copied). Having to type one extra word is not such a burden that you should add cognitive overhead each time someone not intimately familiar with the language has to read your code.
I think the concept of returning by default is fundamental enough that doing so or not is mostly a matter of what you're used to. If I'd started out with Elixir or Ruby I'd probably find it strange that I have to manually return stuff from a function.
Furthermore, at this point ES6 is common enough that knowing at least some of the core additions (among them arrow functions with their implicit return) should be something any front-ender knows.
This is used for readability and to avoid hoisting that can be confusing.