Javascriptでスタックから要素をポップする

例

class Stack {
   constructor(maxSize) {
      // Set default max size if not provided
      if (isNaN(maxSize)) {
         maxSize = 10;
      }
      this.maxSize = maxSize; // Init an array that'll contain the stack values.
      this.container = [];
   }

   // A method just to see the contents while we develop this class
   display() {
      console.log(this.container);
   }

   // Checking if the array is empty
   isEmpty() {
      return this.container.length === 0;
   }
   
   // Check if array is full
   isFull() {
      return this.container.length >= maxSize;
   }

   push(element) {
      // Check if stack is full
      if (this.isFull()) {
         console.log("Stack Overflow!");
         return;
      }
      this.container.push(element);
   }
}

pop() {
   // Check if empty
   if (this.isEmpty()) {
      console.log("Stack Underflow!");
      return;
   }
   this.container.pop();
}

let s = new Stack(2);
s.display();
s.pop();
s.push(20);
s.push(30);
s.pop();
s.display();

[]
Stack Underflow!
[ 20 ]