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JavaScript JavaScript Foundations Functions Return Values

Mark Bradshaw
PLUS
Mark Bradshaw
Courses Plus Student 7,658 Points
Posted by Mark Bradshaw
Mark Bradshaw
Courses Plus Student 7,658 Points

Need assistance with a javascript quiz question

Here's the question:

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.

Gareth Borcherds
Gareth Borcherds
9,372 Points
Gareth Borcherds
Gareth Borcherds
9,372 Points

Before just giving you the answer, what are some code things you have tried? Where have you gotten with trying to do this? It's always best if we can help you edit code you've tried rather than giving out answers.

Mark Bradshaw
Mark Bradshaw
Courses Plus Student 7,658 Points
Mark Bradshaw
Mark Bradshaw
Courses Plus Student 7,658 Points

Sorry Gareth, I feel like I've tried everything. Here's what I setup so far:

function arrayCounter ([1, 2, 3]) {}

1 Answer

Gareth Borcherds
Gareth Borcherds
9,372 Points
Gareth Borcherds
Gareth Borcherds
9,372 Points

Okay, so far you are correct, I would just make the array a variable rather than an actual array. So we start with

function arrayCounter (array) {

}

Now, the next step is that we need to return the length of the array. Do you know how to get the length of an array?

Mark Bradshaw
Mark Bradshaw
Courses Plus Student 7,658 Points
Mark Bradshaw
Mark Bradshaw
Courses Plus Student 7,658 Points

I do. Inside of the curly braces I would add console.log(array.length).

Gareth Borcherds
Gareth Borcherds
9,372 Points
Gareth Borcherds
Gareth Borcherds
9,372 Points

Okay, so that would log it to the console. To actually return the value you would use return array.length;

So now our code looks like this:

function arrayCounter (array) {

return array.length;
}

Now however, we don't know if the variable passed in as array is actually an array. We need to add a check to see if the variable is a string, number, or undefined. So we need an if statement. Do you know how we check the type of variable something may be and put it in an if statement? Once we get that, we'll be complete.

Mark Bradshaw
Mark Bradshaw
Courses Plus Student 7,658 Points
Mark Bradshaw
Mark Bradshaw
Courses Plus Student 7,658 Points

This is where I'm lost in this process. Can you explain how the if statement would be applied here? I know that it would go within the curly braces but I don't know what should be equal to what.

Gareth Borcherds
Gareth Borcherds
9,372 Points
Gareth Borcherds
Gareth Borcherds
9,372 Points

So we are going to use the function typeof and put it in the if statement. If our statement returns true then we will return 0, else we'll return the length.

function arrayCounter (array) {
if (  typeof array === 'string' || typeof array === 'number' || typeof array === 'undefined') { 
        return 0;
    }

return array.length;
}

Does that make sense?