Using 'return'

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#1

I created a for loop that wanted to check for a “.” or a “!” and increment the value of sentenceCount every time it finds one:

function sentCount() { 
for (let i = 0; i < storyChar.length; i++) {  if (storyChar[i] === '.' || storyChar[i] === '!' ){
   sentenceCount ++
    }
  }
}

When I first wrote this function I had the function return sentenceCount++ and when I called the function and then used console.log(sentenceCount); I got a total of 0.

function sentCount() { 
for (let i = 0; i < storyChar.length; i++) {  if (storyChar[i] === '.' || storyChar[i] === '!' ){
   return sentenceCount ++
    }
  }
}

In an effort to fix my code I deleted return, because I realised I wasn’t sure if it needed return or not, and voila the function suddenly started to work!

This has drawn my attention to the fact that I don’t really understand when return is needed and when it is not. And I’m not sure why return broke my function.

Can anyone shed some light on this?

Before posting this I did some testing myself… I just re wrote the function to include a return statement:

function sentCount() { 
for (let i = 0; i < storyChar.length; i++) {  if (storyChar[i] === '.' || storyChar[i] === '!' ){
   sentenceCount ++
    }
  }
  return sentenceCount
}

and then instead of console logging the variable “sentenceCount”, I wrote console.log(sentCount()); and got the correct answer.

So maybe I just answered my own question… If I use return that means that the function will return its own value i.e. that function now = a value. In this case sentCount() = 12.

So the function itself now is almost like its own variable… with the return statement included the function = 12, and without the return statement the function doesn’t have a value of its own. And so including the return statement means that I don’t have to call the statement and then console log the variable separately.

It also means that I can declare my variable(in this case sentenceCount) within the function itself so that it doesn’t have to have global scope and therefore I have cleaner code.

So maybe I just answered my own question in the process of writing this post, but I could be missing something and perhaps someone else might find this useful so I’ll post anyway…

Here’s the final variation of the function I created

function sentCount() { 
  let sentenceCount = 0
for (let i = 0; i < storyChar.length; i++) {  if (storyChar[i] === '.' || storyChar[i] === '!' ){
  sentenceCount ++
    }
  }
  return sentenceCount
}
#2

You’ve pretty much answered your own question! Basically, return hands data back to the caller. This means that you allow the result that you got in the function to be used outside of the function. Another thing about return is that it ends the function. All code after a return that is still in a function won’t be run:

function aFunction(param){
return param;
console.log("hi");//won't be logged
}

I hope this helps!

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#3

That extra bit of info is good to know. I remember building a function that had multiple returns in it and didn’t know why it wouldn’t work. Now I know I was doing some serious damage with my lack of understanding of return.

1 Like
#4

That ‘aha!’ moment is an awesome feeling :slight_smile:

As @codeneutrino mentioned, return ends the function. Return ‘broke’ your function because the first iteration of the for loop returned a value - ending the execution. The first value of i is 0 and that is why it returned 0. The correct value is printed when you move the return out of the for loop because you allowed the loop to run completely before you return the value.

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