Class Stack

stacks/queue-via-stacks.js:39–59

}

class Stack {
  constructor() {
    this.data = [];
  }
  size() {
    return this.data.length;
  }
  isEmpty() {
    return this.size() === 0;
  }
  push(value) {
    this.data.push(value);
  }
  pop() {
    return this.data.pop();
  }
  peek() {
    if (this.isEmpty()) return null;
    return this.data[this.size() - 1];
  }
}