diff --git a/src/arrayMethodJoin.js b/src/arrayMethodJoin.js
index 3a62201c..fbcf4904 100644
--- a/src/arrayMethodJoin.js
+++ b/src/arrayMethodJoin.js
@@ -4,8 +4,21 @@
  * Implement method join
  */
 function applyCustomJoin() {
-  [].__proto__.join2 = function(separator) {
-    // write code here
+  [].__proto__.join2 = function(separator = ',') {
+    const arrLength = this.length;
+    let joinedString = '';
+
+    for (let i = 0; i < arrLength; i++) {
+      if (this[i] !== null && this[i] !== undefined) {
+        joinedString += this[i];
+      }
+
+      if (i !== arrLength - 1) {
+        joinedString += separator;
+      }
+    }
+
+    return joinedString;
   };
 }