# Write Higher Order Arrow Functions ES6

Tell us what’s happening:
I dont seem to understand why squaredIntegers doesnt not return [16, 1764, 36]. Its returning [ 4, 42, 6 ]

``````
const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34];
const squareList = (arr) => {
"use strict";
// change code below this line
const squaredIntegers = arr.filter((val) => {
if(val > 0 && Math.floor(val) == val && Math.ceil(val) == val) {
return val * val;
}
});
// change code above this line
return squaredIntegers;
};
const squaredIntegers = squareList(realNumberArray);
console.log(squaredIntegers);
``````

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1 Like

You aren’t using `filter` correctly. All `filter` does is remove values from an array. Any time the filter function does not return a truthy value, the array item is removed. If it returns a truthy value, then the array item stays (and is not changed).

You may want to look at `array.map()`.

To get some idea, what we are talking about:

``````const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34];

// filter the array
const filteredArray = realNumberArray.filter(
n => n > 0 && Math.floor(n) == n && Math.ceil(n) == n
);
console.log(filteredArray);

// map the array
const squared = filteredArray.map((n) => n ** 2);
console.log(squared);
``````

You can try to implement these two steps into one.

Much more readable and understandable solution:

``````const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34];

const squareList = (arr) => {
'use strict';

const squaredIntegers = arr
// filter the array with built-in function
.filter((m) => Number.isInteger(m))
// return for every filtered value new value
.map((n) => n ** 2);

return squaredIntegers;
};

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

And a last, shortened version:

``````const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34];

const squareList = (arr) => arr.filter((m) => Number.isInteger(m)).map((n) => n ** 2);

const squaredIntegers = squareList(realNumberArray);
console.log(squaredIntegers);
``````
2 Likes

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Thank you.

3 Likes

Thanks. Helped me clear up some concepts.