2634. Filter Elements from Array
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 thearri- index ofarr[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.
Example 1:
Input: 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
Example 2:
Input: 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
Example 3:
Input: 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
GoogleHints open one at a time
Hint 1
Start by declaring a new array which will eventually be returned.
Hint 2
In Javascript, there is the concept of "truthiness" and "falsiness". Values such as 0, undefined, null, and false are falsy. Most values are truthy: 1, {}, [], true, etc. In Javascript, the contents of if-statements don't need to be booleans. You can say "if ([1,2,3]) {}", and it's equivalent to saying 'if (true) {}".
Hint 3
Loop over each element in the array. If fn(arr[i]) is truthy, push it to the array.
Loading editor…
1/**
2 * @param {number[]} arr
3 * @param {Function} fn
4 * @return {number[]}
5 */
6var filter = function(arr, fn) {
7
8};
Starter codeJavaScriptSpaces: 4
Loading editor…
1/**
2 * @param {number[]} arr
3 * @param {Function} fn
4 * @return {number[]}
5 */
6var filter = function(arr, fn) {
7
8};
Starter codeJavaScriptSpaces: 4
Examples
Input
function greaterThan10(n) { return n > 10; }
[0,10,20,30]Input
function firstIndex(n, i) { return i === 0; }
[1,2,3]Input
function plusOne(n) { return n + 1 }
[-2,-1,0,1,2]Your code is saved on this device.Solution