Extra Credit Fizz Buzz (is this correct)?

Good effort, Derek Dawes . :)

Going the else if route as suggested is a good way to go, just be sure they are separate words as there is no elseif in JavaScript.

As Shawn Flanigan has also suggested, be sure to keep the most unique cases at the top of the conditional chain to ensure they will be considered.

I have included a few different ways to write the same thing below. The conditional logic is placed in a function called DivisibleBy3Or5 passing in a Number as an argument. I have also created a function called cout which takes a String so it's quicker and easier to type out console.log more than once:

Using if else:

var x = 1;

function DivisibleBy3Or5(num) {
    if (num % 3 === 0 && num % 5 === 0) {
        return 'fizzbuzz';
    } else if (num % 3 === 0) {
        return 'fizz'; 
    } else if (num % 5 === 0) {
        return 'buzz';
    } else {
        return num.toString();
    }
}

function cout(str) {
    console.log(str);
}

cout('Start of loop');
while (x <= 100) {
    cout(isDivisibleBy3Or5(x));
    x += 1;
}

• For the rest of the examples I have only included the DivisibleBy3Or5 function.

Using if only for a little less screen space:

function DivisibleBy3Or5(num) {
    if (num % 3 === 0 && num % 5 === 0) return 'fizzbuzz';
    if (num % 3 === 0) return 'fizz'; 
    if (num % 5 === 0) return 'buzz';
    if (!num % 3 === 0 || !num % 5 === 0) return num.toString();
}

Same as the if else example, but slightly less code using a ternary operator conditional statement:

function DivisibleBy3Or5(num) {
    // This could, technically, be all on one line,
    // but separated for readability
    return (num % 3 === 0 && num % 5 === 0)
        ? 'fizzbuzz'
        : (num % 3 === 0)
        ? 'fizz'
        : (num % 5 === 0)
        ? 'buzz'
        : num.toString();
}

Looks pretty good. My only critique would be that with your conditional statements, you are going to check each if statement. I would think of a logical way of ordering these using if and elseif statements. That way, if it's divisible by one number, you don't need to check the others.