Can someone convert this arrow function into Normal function?

I am unable to convert this arrow function into Normal function. I have tested this in the console panel of the chrome. This code was taken from freecodeCamp.org in the Es6 lesson

//This is what I have tried. The final output result is showing undefined


const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34, -2];
const squareList = function(arr) {
    "use strict";
    const squaredIntegers = function(num) {
        (function() {
            arr.filter(Number.isInteger(num) && num > 0);
        });       
        return squaredIntegers;
    } 
}

const squaredIntegers = squareList(realNumberArray);
console.log(squaredIntegers);

//Here is the Arrow function I was trying to convert

const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34, -2];
const squareList = (arr) => {
    "use strict";
    const squaredIntegers = arr.filter(num => Number.isInteger(num) && num > 0);
    return squaredIntegers;
};
const squaredIntegers = squareList(realNumberArray);
console.log(squaredIntegers);


//The code should output this
[4, 42, 6];