Fast implementation of a queue in TypeScript/JavaScript

Queue.ts

class Queue {
  private readonly queue: any[];
  private start: number;
  private end: number;

  constructor(array: any[] = []) {
    this.queue = array;

    // pointers
    this.start = 0;
    this.end = array.length;
  }

  isEmpty() {
    return this.end === this.start;
  }

  dequeue() {
    if (this.isEmpty()) {
      throw new Error("Queue is empty.");
    } else {
      return this.queue[this.start++];
    }
  }

  enqueue(value: any) {
    this.queue.push(value);
    this.end += 1;
  }

  toString() {
    return `Queue (${this.end - this.start})`;
  }

  [Symbol.iterator]() {
    let index = this.start;
    return {
      next: () =>
        index < this.end
          ? {
              value: this.queue[index++]
            }
          : { done: true }
    };
  }
}

export default Queue;

It has great time complexity but at the sacrifice of space complexity after many enqueues and dequeues. This is a nice and simple implementation, thanks for sharing. 👍

@lesterfernandez

Yeah - option could be to use a plain object with integer property keys instead of an array

Then you can delete the key when it is out of bounds which solves the memory issue