diff --git a/src/arrayMethodJoin.js b/src/arrayMethodJoin.js
index 3a62201c..57048746 100644
--- a/src/arrayMethodJoin.js
+++ b/src/arrayMethodJoin.js
@@ -4,8 +4,23 @@
  * Implement method join
  */
 function applyCustomJoin() {
-  [].__proto__.join2 = function(separator) {
-    // write code here
+  [].__proto__.join2 = function(separator = ',') {
+    let result = '';
+    const readySeparator = separator !== undefined ? String(separator) : ',';
+
+    for (let i = 0; i < this.length; i++) {
+      const value = this[i];
+
+      if (value !== undefined && value !== null) {
+        result += value;
+      }
+
+      if (i !== this.length - 1) {
+        result += readySeparator;
+      }
+    }
+
+    return result;
   };
 }