Deque structure - array based

Deque.js

class Deque {
  constructor() {
    this.items = [];
  }
  addFront(item) {
    this.items.unshift(item);
  }
  addBack(item) {
    return this.items.push(item);
  }
  removeFront() {
    return this.items.shift();
  }
  removeBack() {
    return this.items.pop();
  }
  peekFront() {
    return this.items[0];
  }
  peekBack() {
    return this.items[this.items.length -1];
  }
  clear() {
    this.items = [];
  }
  isEmpty() {
    return this.items.length === 0;
  }
  size() {
    return this.items.length;
  }
}