Adressing issue Yet-Another-Series#103 - Added js-queues.js

Data_Structures/queues/js-queues.js

@@ -0,0 +1,84 @@
+/* 
+Queue_DataStructure implementation using dynamic memory allocation 
+
+Methods : 
+	Push(value) - Push value into the Queue
+	Pop()       - Delete front element of Queue
+	Front()     - Get the front element element
+	isEmpty()   - Returns Boolean whether Queue is empty (true) or not (false)
+*/
+
+// Class for node with members for value and next node
+class Node{
+  constructor(v){
+    this.val = v;
+    this.nxt=null;
+  }
+}
+
+// Class Queue
+class Queue{
+  constructor(){
+    this.first=null;
+    this.last=null;
+  }
+
+  // Add element from back
+  push(n){
+    var newElem = new Node(n);
+    if(this.last){
+      this.last.nxt = newElem;
+      this.last = newElem
+    }
+    else{
+      this.last=newElem;
+      this.first=newElem;
+    }
+  }
+
+  // Delete element from front
+  pop(){
+    if(this.first){
+      this.first = this.first.nxt;
+    }
+    else
+      throw new Error("Queue Empty!");
+  }
+
+  // Get front element
+  front(){
+    if(!this.isEmpty())
+      return this.first.val;
+    else
+      throw new Error("Queue Empty!");
+  }
+
+  // Check if Queue is empty
+  isEmpty(){
+    return !(this.first);
+  }
+
+}
+
+
+
+// Sample implementation : 
+
+
+
+// Create a new Queue
+var q = new Queue;
+
+// Push 10, 20 and 30
+q.push(10);
+q.push(20);
+q.push(30);
+console.log(q.front()); // Print front element
+q.push(40); // Insert 40
+q.pop(); // Pop element
+console.log(q.front()); // Print front element
+// Pop elements
+q.pop();
+q.pop();
+console.log(q.front()); // Print front element
+q.pop(); // Pop element