diff --git a/src/queue/queue-data-structure.js b/src/queue/queue-data-structure.js
index 98ac0fd0..2d8627fc 100644
--- a/src/queue/queue-data-structure.js
+++ b/src/queue/queue-data-structure.js
@@ -5,23 +5,32 @@ class Queue {
   }
 
   canEnqueue() {
-    // ... your code goes here
+    return this.queueControl.length<this.MAX_SIZE?true:false;
   }
 
   isEmpty() {
-    // ... your code goes here
+    return this.queueControl.length===0? true : false;
   }
 
   enqueue(item) {
-    // ... your code goes here
+    if (this.canEnqueue()){
+      this.queueControl.push(item);
+    } else {
+      throw new Error('QUEUE_OVERFLOW');
+    }
+    return this.queueControl;
   }
 
   dequeue() {
-    // ... your code goes here
+    if (this.isEmpty()) {
+      throw new Error('QUEUE_UNDERFLOW');
+    } else {
+      return this.queueControl.shift()
+    }
   }
 
   display() {
-    // ... your code goes here
+    return this.queueControl;
   }  
 }
 
diff --git a/src/stack/stack-data-structure.js b/src/stack/stack-data-structure.js
index 1106f6f3..74e07a89 100644
--- a/src/stack/stack-data-structure.js
+++ b/src/stack/stack-data-structure.js
@@ -5,23 +5,32 @@ class Stack {
   }
 
   canPush() {
-    // ... your code goes here
+    return this.stackControl.length<this.MAX_SIZE?true:false;
   }
 
   isEmpty() {
-    // ... your code goes here
+    return this.stackControl.length===0? true : false;
   }
 
   push(item) {
-    // ... your code goes here
+    if (this.canPush()){
+      this.stackControl.push(item);
+    } else {throw new Error('STACK_OVERFLOW');
   }
+  return this.stackControl;
+}
 
   pop() {
-    // ... your code goes here
+    if (!this.isEmpty()) {
+      return this.stackControl.pop();
+    } else {
+      throw new Error('STACK_UNDERFLOW');
+    }
+    
   }
 
   display() {
-    // ... your code goes here
+    return this.stackControl;
   }  
 }