Filter Elements from Array Lab

Easy
32
3
64.0% Acceptance

In this lab, you will implement a custom filtering function that takes an integer array arr and a filtering function fn and returns a new array containing elements where fn(arr[i], i) evaluates to a truthy value. Please note that you should not use the built-in Array.filter method to solve this lab.

Lab description

Your task is to create a custom filtering function that filters elements in an array based on a given filtering function, fn. The function should take an array arr and a filtering function fn as arguments. It should return a new array where only the elements that satisfy the filtering function are included.

Make sure to consider the following points:

  • Your function should work for arrays of different lengths and with elements of different types.
  • It should handle truthy and falsy values correctly.

Here are some example cases to help you understand the problem better:

Example 1:

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

const newArray = filter(arr, fn); // [20, 30]

In this example, the function filters out values that are not greater than 10. The returned array should only contain the values 20 and 30.

Example 2:

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

const newArray = filter(arr, fn); // [1]

In the second example, fn also accepts the index of each element. The function removes elements not at index 0, so the returned array should only contain the value 1.

Example 3:

const arr = [-2, -1, 0, 1, 2];
const fn = function plusOne(n) {
    return n + 1;
}

const newArray = filter(arr, fn); // [-2, 0, 1, 2]

In the last example, the function filters out falsey values such as 0. The returned array should only include the values -2, 0, 1, and 2.

Please implement your solution in the provided index.js file. Don't forget to export your filter function so it can be tested in the evaluation script.

Happy coding!