Problem Explanation - Use Higher-Order Functions map, filter, or reduce to Solve a Complex Problem

JavaScript
#1

The Challenge is
We have defined a function named squareList . You need to complete the code for the squareList function using any combination of map() , filter() , and reduce() so that it returns a new array containing only the square of only the positive integers (decimal numbers are not integers) when an array of real numbers is passed to it. An example of an array containing only real numbers is [-3, 4.8, 5, 3, -3.2] .

Note: Your function should not use any kind of for or while loops or the forEach() function.

So far am able to come up with this solution

const squareList = (arr) => {

  // Only change code below this line

  return arr.filter(mum => mum > 0)

  // Only change code above this line

};

const squaredIntegers = squareList([-3, 4.8, 5, 3, -3.2]);

console.log(squaredIntegers); // output [4.8,  5,  3]

It won’t filter properly because of the decimal number that is still in the array. Can any help me out?

#2

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#3

at this time the only condition in your code is the callback, which is mum => mum > 0, and this is filtering out negative numbers

to have only whole integers, you need to add a second condition.

Do you think you can google a bit and see what you find?
There are many different ways for this

#4

I have tried Google, i couldn’t find any helpful hint. I also checked freeCodeCamp’s guide for the answer but i don’t seem to understand the solution.

#5

Thanks, i will take note of that next time

#6

you need to check if the number is a whole number or have decimals

If I google “javascript test whole number” there are various interesting things to read. Also, just scrolling through the results, the third result is a method called isInteger().

Check if that can be useful.

#7

Finally i got it, now i fully comprehend how the whole magic went…

const squareList = (arr) => {
  // Only change code below this line
  return arr.filter(num => num  > 0 && Number.isInteger(num))
.map(num => Math.pow(num, 2));
  // Only change code above this line
};

const squaredIntegers = squareList([-3, 4.8, 5, 3, -3.2]);
console.log(squaredIntegers);

Thanks alot, i really appreciate.

#8