The top is the pointer that tracks the position where new elements should be stored. If the top is equal to -1 (which is its starting point), then the stack is empty. If the top is equal to MAXSIZE, it means the stack is full. The size of this specific stack is 9.
Now check out these below methods:
1class Stack {
2 // Array is used to implement stack
3 constructor() {
4 this.items = [];
5 }
6
7 // Functions we'll need
8 push(val) {
9 // Push element into the items array
10 this.items.push(val);
11 }
12 pop() {
13 // Return top most element in the stack
14 // and remove it from the stack
15 if (!this.items.length) return "The stack has an underflow!";
16 return this.items.pop();
17 }
18 // peek()
19 // getSize()
20 // print()
21}