code added

Author: Bharat2044

06_filterElementsFromArray.js

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+// Question Link: https://leetcode.com/problems/filter-elements-from-array/description/?envType=study-plan-v2&envId=30-days-of-javascript
+// Solution Link: https://leetcode.com/problems/filter-elements-from-array/solutions/5434736/2-javascript-easy-solution-using-for-loop-and-foreach-loop/
+
+/*
+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 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.
+
+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
+-10^9 <= arr[i] <= 10^9
+*/
+
+
+
+/**
+ * @param {number[]} arr
+ * @param {Function} fn
+ * @return {number[]}
+ */
+
+// 1st Approch: Using for Loop - TC = O(n), SC = O(n)
+/*
+var filter = function(arr, fn) {
+    let filteredArr = [];
+    let x = 0;
+
+    for (let i = 0; i < arr.length; i++) {
+        if (fn(arr[i], i)) {
+            // filteredArr.push(arr[i]);
+            filteredArr[x++] = arr[i];
+        }
+    }
+
+    return filteredArr;
+};
+*/
+
+// 2nd Approach: Using forEach Loop - TC = O(n), SC = O(n)
+var filter = function(arr, fn) {
+    let filteredArr = [];
+
+    arr.forEach((val, index) => {
+        if (fn(val, index)) {
+            filteredArr.push(val);
+        }
+    });
+
+    return filteredArr;
+};