class Stack {
constructor(){
this.data = [];
}
push(value){
if(!value) return null
this.data.push(value)
}
peek(){
if(this.data.length === 0) return null
return this.data[this.data.length-1] ;
}
pop(){
if(this.data.length === 0) return null
return this.data.pop()
}
totalItem(){
return this.data.length;
}
}
const stack = new Stack();
stack.push(9);
stack.push(90);
stack.push(900);
stack.push(9000);
stack.push(90000);
stack.push(900000);
console.log(stack)
console.log(stack.peek())
console.log(stack.pop())
console.log(stack.pop())
console.log(stack.pop())
console.log(stack.pop())
console.log(stack.pop())
console.log(stack.pop())
console.log(stack.pop())
console.log(stack.pop())
console.log(stack.pop())
