dsa_javascript/queue.html at main · prakash-dev-code/dsa_javascript · GitHub

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <h1>Queue with javascript</h1>

    <script>
      let queue = [];
      let queueSize = queue.length;
      let maxSize = 6;

      function enqueue(value) {
        if (queueSize >= maxSize) {
          console.log("Queue is full. Can't enqueue.");
          return;
        }

        queue[queueSize] = value;
        queueSize++;
      }

      function dequeue() {
        if (queueSize === 0) {
          console.log("Queue is empty. Can't dequeue.");
          return;
        }

        let dequeueValue = queue[0];

        for (let i = 0; i < queueSize - 1; i++) {
          queue[i] = queue[i + 1];
        }

        queueSize--;
        queue.length = queueSize;

        return dequeueValue;
      }

      enqueue(50);
      enqueue(100);
      enqueue(150);
      enqueue(200);

      dequeue();
      dequeue();

      // console.log(queue);

      // circular queue

      class Queue {
        constructor(size) {
          this.max = size;
          this.items = new Array(size);
          this.currentSize = 0;
          this.rear = -1;
          this.front = -1;
        }
        enqueue(val) {
          if (this.currentSize != this.max) {
            if (this.rear == this.max - 1) {
              this.rear = 0;
            } else {
              this.rear++;
            }
            this.items[this.rear] = val;
            this.currentSize++;
            if (this.front == -1) {
              this.front = this.rear;
            }
          }
        }
        dequeue() {
          if (this.currentSize != 0) {
            this.items[this.front] = null;
            if (this.front == this.max - 1) {
              this.front = 0;
            } else {
              this.front++;
            }
            this.currentSize--;
          } else {
            this.front = -1;
            this.rear = -1;
            alert("queue is empty");
          }
        }
      }

      let queueCircle = new Queue(5);
    </script>
  </body>
</html>