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JavaScript JavaScript Foundations Functions Return Values

nicholas maddren
nicholas maddren
12,793 Points
Posted by nicholas maddren
nicholas maddren
12,793 Points

What is the question asking of me?

I feel as if I've just watched a different video for the actual task.

Here is my code:

   function arrayCounter(array){if
      (typeof === 'Undefined')
      return 0;
                                  }
      return array.length
      };

And here is the question:

Around line 17, create a function named 'arrayCounter' that takes in a parameter which is an array. The function must return the length of an array passed in or 0 if a 'string', 'number' or 'undefined' value is passed in.

I haven't learnt about adding a parameter which is an array yet so I don't know how to do this? Any help would be great :)

2 Answers

Dino Paškvan
PLUS
Dino Paškvan
Courses Plus Student 44,108 Points
Dino Paškvan
Dino Paškvan
Courses Plus Student 44,108 Points

Passing an array to a function is in no way different from passing a variable with any other data type.

Let's say you have an arrayPrinter function that prints an array. It doesn't matter how it works or even what it does. It takes a single parameter — an array. You can pass that parameter as a variable or as an array literal:

var myArr = [0, 1, 2, 3, 4, 5];
arrayPrinter(myArr); // just like any other variable

// or

arrayPrinter([0, 1, 2, 3, 4, 5]); // an array literal is still a single parameter

Now, as the task says, you have to check if the parameter passed to the function is a number, string or undefined. If it is one of those, you return 0, otherwise you return the length.

Your first attempt is actually somewhat close to what you need to do. It's important to know that the typeof operator needs to work on something. To check if something is undefined, you need to specify that something:

if (typeof paramName === "undefined") {
  // do something
}

Also, typeof returns all lower-caps strings.

Next, you need to use the logical or operator (||) to do all of those checks in a single if. You can read about how that works in another thread.

So, when you combine all of that, you get something like this:

function arrayCounter(array) {
  if (typeof array === "undefined" || typeof array === "number" || typeof array === "string") {
    return 0;
  }
  return array.length;
}
Philip Cox
Philip Cox
14,818 Points
Philip Cox
Philip Cox
14,818 Points

Sorry to hijack the thread, but how do you add those code snippets please?

Dino Paškvan
Dino Paškvan
Courses Plus Student 44,108 Points

Check the Markdown Cheatsheet for more info, but the gist of it is that you need to use three backticks (```), not three single quotes.

Jon Edwards
Jon Edwards
7,913 Points
Jon Edwards
Jon Edwards
7,913 Points

Can anyone please explain why sometimes you use the "else" in the function, while other times it seems that it is just implied and the else is not even typed in? Is it simply a shorthand version? I've seen many solutions to this problem on the forums, some using else, others just leaving it off. Thanks!

Philip Cox
Philip Cox
14,818 Points
Philip Cox
Philip Cox
14,818 Points

Maybe something like this?

functionarrayCounter(array) {
  if ( Array.isArray(array) ) {
    return array.length;
  } else {
    return 0; 
  }
}