Functions, Arrays and Return Values. Task 5

Brian,

Let's break this down step by step.

1) They want you to declare a function called 'arrayCounter'. By now, we should know how to do this:

function arrayCounter() {
}

2) Make it so the function accepts one parameter, which will be an array. You can name this parameter anything you want; for clarity's sake, let's call it 'arrayParam':

function arrayCounter(arrayParam) {
}

3) Inside your function, you're going to return some value based on what the passed in argument is. Thus, we know we'll want to set up an 'if' statement:

function arrayCounter(arrayParam) {
    if() {
        //if return value here
    } else {
        //else return value here
    }
}

4) The condition we want to check for is the type of the parameter passed in. If you'll recall from the lesson, there is a handy feature for this built into JavaScript called 'typeof':

function arrayCounter(arrayParam) {
    if(typeof arrayParam) {
        //if return value here
    } else {
        //else return value here
    }
}

5) To make this simple, we can use a negative conditional to check if the value of our parameter is not what we're looking for. We should also know that an array is really just a list-like object, so we'll check if our parameter is not an object, and then return the corresponding value:

function arrayCounter(arrayParam) {
    if(typeof arrayParam !== 'object') {
        //we'll get here if the type of arrayParam is NOT an object, and thus NOT an array
        return 0;
    } else {
        //else return value here
    }
}

6) And so, if the type of arrayParam IS indeed an object, and thus IS an array, we want to return the length of that array, which we also recall from our previous lessons:

function arrayCounter(arrayParam) {
    if(typeof arrayParam !== 'object') {
        //we'll get here if the type of arrayParam is NOT an object, and thus NOT an array
        return 0;
    } else {
        //we'll get here if the type of arrayParam IS an object, and thus IS an array, and since it IS an array, we can use array properties
        return arrayParam.length;
    }
}

Hope this has helped to break things down and show you the thought process that goes into putting a function like this together!

Erik