Question

For example, are these two effectively the same?

someFunction(val, callback){
    callback(val);
};

and

someFunction(val, callback){
    callback(val);
    return;  // necessary?
};

Answer 1

Yes, they are the same. If your function does not return a value then you can either omit the return statement or use it with no argument; in both cases a call to the function returns “undefined”.

function f1(){};
typeof(f1()); // => "undefined"

function f2(){return;};
typeof(f2()); // => "undefined"