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

JavaScript
1

Tell us what’s happening:
I don’t understand how to get only integers…
I need the hint spelled out in plain English to better understand what is happening…

.filter(num => num > 0 && num % parseInt(num) === 0)

…and number divided by a binary parseInt? strictly equal to zero???

what?

Your code so far
const squareList = arr => {
// Only change code below this line
return arr
.filter(arr => arr > 0)

.map(arr => Math.sqrt(arr))
// Only change code above this line
};

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

[ 2.1908902300206643, 2.23606797749979, 1.7320508075688772 ]

const squareList = arr => {
  // Only change code below this line
  return arr
  .filter(arr => arr > 0)

  .map(arr => Math.sqrt(arr))
  // Only change code above this line
};

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

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36

Challenge: Functional Programming - Use Higher-Order Functions map, filter, or reduce to Solve a Complex Problem

Link to the challenge:

2

You are filtering for positive numbers but you aren’t filtering for only integers.

Also, you want the square of each number, not the square root.

3

ok that helps my Math.sqrt line … Thank You

I replaced it with .map(arr => arr * 2)

4

That’s not squaring a number. That’s multiplying it by 2. Squaring a number means multiplying it by itself.

5

ooops arr * arr
thanks

6

this little beauty is tripping me up … num % parseInt(num) === 0)

7

That is a condition to return only integers and not decimals. The modulo % means that the remainder of a division must be zero.

" The modulo operation (abbreviated “mod”, or “%” in many programming languages ) is the remainder when dividing. For example, “5 mod 3 = 2” which means 2 is the remainder when you divide 5 by 3."

The main purpose of using the parseInt function is to extract a number from a string . This turns the returned value to an actual number.

1 Like
8

THANK YOU DobarBREND! Excellent!

1 Like
9

Also, you can use the Number.isInteger() method I think is easier to read in the long run.

1 Like
10

awesome, I’m gonna try it…

Thank You

11

.filter(arr => arr > 0 && Number.isInterger(arr))

it says isInterger is not a fuction

12

Yes, but Number.isInteger is :slightly_smiling_face:

13

I have Number in the code

.filter(arr => arr > 0 && Number.isInterger(arr))

14

I was trying to point out that you spelled it wrong. You have an extra r in there.

1 Like
15

oh man … thank you bbsmooth

I’m using my new laptop after I finish this certifiation

16

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