class Node {
constructor(value) {
this.value = value;
this.next = null;
}
}
class Stack {
constructor() {
this.top = null;
this.bottom = null;
this.length = 0;
}
peek() {
return this.top.value;
}
push(value) {
let node = new Node(value);
if (this.length === 0) {
this.top = node;
this.bottom = node;
this.length++;
return this;
}
node.next = this.top;
this.top = node;
this.length++;
return this;
}
pop() {
if (this.length === 0) {
return null;
}
if (this.length === 1) {
let val = this.top.value;
this.top = null;
this.bottom = null;
this.length = 0;
return val;
}
let val = this.top.value;
let next = this.top.next;
this.top = next;
this.length--;
return val;
}
isEmpty() {
return (this.length === 0);
}
// print the elements in the stack
printList() {
const values = [];
let node = this.top;
while (node !== null) {
values.push(node.value);
node = node.next;
}
console.log(values.join(" | "));
}
}
const myStack = new Stack();
console.log(myStack.isEmpty());
myStack.push(10);
myStack.push(20);
myStack.push(30);
myStack.push(40);
console.log(myStack.peek());
myStack.printList();
console.log(myStack.pop());
myStack.printList();
console.log(myStack.isEmpty());
console.log(myStack.length);
console.log(myStack);
