Javascript Filter integers

I'm learning javascript on FreecodeCamp. And, the solution of my problem doesn't help me more. We have to filter integers in an array which is saved in const variable.

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

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

and I cannot understand really this part num % parseInt(num) === 0 ).map( (num) => Math.pow(num, 2) );

Why using parseint() method and Math.pow. Someone could explain me why?

thanks.

parseInt(num) gives an integer part of num, for example, parseInt(3.14) === 3 //true. Using num % parseInt(num) basically gives a difference between the number and its integer part. If it isn't 0, the number is thrown out. Math.pow(num) gives a squared number, which is returned to the new array. Though, num * num is faster in that regard, not having to include a module and to call an object property.

Other than that, the code is very crammed in the solution, and I would suggest to break it down to improve readability. Seems like the style in which it is written adds to the confusion.