Is it better to wrap code into an 'IF' statement, or is it better to 'short circuit' the function and return? [closed]

Answer 1

Personal choice. For me, if there are some "stop" conditions I can check at the beginning of the method, I prefer using the "return" pattern. But only if I can do them all in the beginning of the method.

Answer 2

In my opinion, as a best practice, I think it is more important to consistently use braces with your control blocks, even if their body is only one line.

Consistent

if ( condition ) {
    statement;
    statement;
}

if ( condition ) {
    statement;
}

Not consistent

if ( condition ) {
    statement;
    statement;
}

if ( condition )
    statement;

But even still, this is completely subjective.

As for when to break out of a function, and levels of indentation, that's subjective too. Research and experience have shown that exiting a function at only one point (the end) is easier to debug, optimize, etc. On the other hand, multiple levels of indentation can make a function difficult to read.

Answer 3

Alternatively, since JavaScript is scheme in disguise

HandleRequestForAlcohol = function(age) { 
    ( IsUnderAge(age) ? RespondUnderAge : ServeAlcohol )();
}

The idiom for selecting the function isn't that important, rather that if you are doing complex validation and then have multiple processes, factor these to separate functions rather than making one big one, unless it's in a very performance critical bit of code.

Answer 4

A general rule I've heard is basically fail early and fail often. You never know when a single line of code is pointing to some super-overloaded setter that's working way harder than you might think. If you can prevent that line of code from being executed - say, by returning early - then your code is going to be exponentially more efficient.

In other words, if you can return early and keep code from executing, do it at every turn - especially if you are concerned at all about performance. This might not be as important in something like JS, I suppose - I'm more of an AS3 guy - but the same logic applies.

If you have a lot of cases, it might be best also to trace out the point of failure in each one - in your example, trace out that this returned early because the age was too low. That'll help other developers who go in and attempt to debug your code, they'll know where things fail and why.

Hope that helps! :)

Answer 5

I prefer the first one, because it's a guard condition and you exit directly. But I don't think there is performance issues with either, just that it's your preference... Both will return execution directly...

Answer 6

I prefer the first one, because it's the process of elimination, where you return out of the function before the program even has to step through the next round of logic. I call it my prereq check - where the function won't execute if it doesn't meet the prereq check

In fact, I do this all the time, for example, the classic one is where i have a function that's expecting an integer and i get a string, i check at the top of the function if it's an integer, NOT if it's not a string or not another object/type, that's just stupid in my book.

It's like a college application to Harvard, a prerequisite:

'I don't want to even want you to come for an interview if you don't have a 3.5GPA or higher!'

:=)