From a33f7e62a1e4fe4cc5158f23fa736da5fdbbc9be Mon Sep 17 00:00:00 2001
From: the-it-weirdo <ddsmegh4@gmail.com>
Date: Sun, 4 Oct 2020 10:31:28 +0530
Subject: [PATCH] Adds Queue in JavaScript. -> Queue/Queue.js

---
 Queue/Queue.js | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 Queue/Queue.js

diff --git a/Queue/Queue.js b/Queue/Queue.js
new file mode 100644
index 00000000..664d7106
--- /dev/null
+++ b/Queue/Queue.js
@@ -0,0 +1,63 @@
+// class definition
+class Queue {
+  constructor(size) {
+    this.size = size;
+    this.data = [];
+  }
+
+  // checks if Queue is empty
+  isEmpty() {
+    return this.data.length === 0;
+  }
+
+  // checks if Queue is full
+  isFull() {
+    return this.data.length === this.size;
+  }
+
+  // Inserts element at the last of the Queue
+  enQueue(element) {
+    if (!this.isFull()) {
+      this.data.push(element);
+    } else {
+      throw Error("Queue overflow.");
+    }
+  }
+
+  // Removes first element from the Queue. 
+  deQueue() {
+    if (this.isEmpty()) {
+      throw Error("Queue underflow.");
+    } else {
+      return this.data.shift();
+    }
+  }
+
+  // Peek at the front of the Queue. This doesn't remove element from the Queue;
+  front() {
+    if (this.isEmpty()) {
+      console.log("Queue is empty.");
+    } else {
+      return this.data[0];
+    }
+  }
+
+  // To print the Queue data.
+  printQueue() {
+    console.log(this.data);
+  }
+}
+
+
+// Usage
+const q = new Queue(5);
+q.enQueue(1); // [1]
+q.enQueue(2); // [1, 2]
+q.enQueue(3); // [1, 2, 3]
+q.enQueue(4); // [1, 2, 3, 4]
+q.enQueue(5); // [1, 2, 3, 4, 5]
+q.front(); // 1
+q.deQueue(); // 5
+q.enQueue(5); // [1, 2, 3, 4, 5]
+q.printQueue(); // prints the Queue data. 
+q.enQueue(6); // Queue Overflow Error