--update: added code for Weaving 2 queues

Author: ashokdey

src/_DataStructures_/Queue/Queue.test.js

@@ -12,19 +12,35 @@ describe('Data Structure : Queue', () => {
       queue = new Queue();
     });
 
-    it('Should add element to a queue', () => {
+    it('Should add() element to a queue', () => {
       queue.add(5);
       expect(queue.data).toEqual([5]);
     });
 
-    it('Should remove an element from the queue', () => {
+    it('Should remove() an element from the queue', () => {
       queue.add(2);
       queue.add(3);
       queue.remove();
 
       expect(queue.data).toEqual([3]);
     });
 
+    describe('peek()', () => {
+      beforeEach(() => {
+        queue.add(2);
+        queue.add(5);
+      });
+
+      it('Should return the elemet to be removed using peek()', () => {
+        expect(queue.peek()).toEqual(2);
+      });
+
+      it('Should not remove the element', () => {
+        expect(queue.peek()).toEqual(2);
+        expect(queue.remove()).toEqual(2);
+      });
+    });
+
     it('Should maintain the order of elements', () => {
       // first in first out
       queue.add(2);

src/_DataStructures_/Queue/index.js

@@ -8,6 +8,10 @@ class Queue {
     return this.data.unshift(element);
   }
 
+  peek() {
+    return this.data[this.data.length - 1];
+  }
+
   remove() {
     return this.data.pop();
   }

src/_DataStructures_/Queue/weave/index.js

@@ -0,0 +1,20 @@
+const Queue = require('../index');
+
+function weaveQueues(first, second) {
+  const weaved = new Queue();
+
+  while (first.peek() || second.peek()) {
+    if (first.peek() !== undefined) {
+      weaved.add(first.remove());
+    }
+
+    if (second.peek() !== undefined) {
+      weaved.add(second.remove());
+    }
+  }
+  return weaved;
+}
+
+module.exports = {
+  weaveQueues,
+};

src/_DataStructures_/Queue/weave/weave.test.js

@@ -0,0 +1,27 @@
+const { weaveQueues } = require('.');
+const Queue = require('../index');
+
+describe('Weave two queues using weaveQueues()', () => {
+  it('Should weave be a function', () => {
+    expect(typeof weaveQueues).toEqual('function');
+  });
+
+  it('Should weave 2 queues', () => {
+    const q1 = new Queue();
+    const q2 = new Queue();
+
+    q1.add('Hello');
+    q2.add(1);
+    q1.add('World');
+    q2.add(2);
+    q2.add(3);
+
+    const q3 = weaveQueues(q1, q2);
+
+    expect(q3.remove()).toEqual('Hello');
+    expect(q3.remove()).toEqual(1);
+    expect(q3.remove()).toEqual('World');
+    expect(q3.remove()).toEqual(2);
+    expect(q3.remove()).toEqual(3);
+  });
+});