2634-Filter-Elements-from-Array

2634. Filter Elements from Array

Easy

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Given an integer array arr and a filtering function fn, return a filtered array filteredArr.

The fn function takes one or two arguments :

• arr[i] - number from the arr
• i - index of arr[i] filteredArr should only contain the elements from the arr for which the expression fn(arr[i], i) evaluates to a truthy value. A truthy value is a value where Boolean(value) returns true.

Please solve it without the built-in Array.filter method.

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Example 1:

arr = [0,10,20,30], fn = function greaterThan10(n) { return n > 10; }
// Output: [20,30]

Explanation:
const newArray = filter(arr, fn); // [20, 30]
The function filters out values that are not greater than 10

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Example 2:

arr = [1,2,3], fn = function firstIndex(n, i) { return i === 0; }
// Output: [1]

Explanation:
fn can also accept the index of each element
In this case, the function removes elements not at index 0

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Example 3:

arr = [-2,-1,0,1,2], fn = function plusOne(n) { return n + 1 }
// Output: [-2,0,1,2]

Explanation:
Falsey values such as 0 should be filtered out

Constraints:

• 0 <= arr.length <= 1000
• 109 <= arr[i] <= 109

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