Created question6.js for Unique elements question.

JavaScript Programs Using Functions/question6.js

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+// Question
+// Write a function uniqueElements(arr) that takes an array of numbers as input and returns a new array containing only the unique elements from the input array. The order of the unique elements in the output array should match their first appearance in the input array.
+// EXAMPLE
+// console.log(uniqueElements([1, 2, 2, 3, 4, 4, 5])); // Output: [1, 2, 3, 4, 5]
+// console.log(uniqueElements([5, 5, 5, 1, 2, 3, 3])); // Output: [5, 1, 2, 3]
+// console.log(uniqueElements([])); // Output: []
+
+
+//ANSWER:-
+function uniqueElements(arr) {
+    const uniqueArray = [];
+    const seen = new Set();
+
+    for (const element of arr) {
+        if (!seen.has(element)) {
+            seen.add(element);
+            uniqueArray.push(element);
+        }
+    }
+
+    return uniqueArray;
+}