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
}
push(value) {
const newTop = new Node(value)
if (this.length === 0) {
this.top = newTop
this.bottom = newTop
} else {
const holdingPointer = this.top
this.top = newTop
this.top.next = holdingPointer
}
this.length++
return this
}
pop() {
if (this.top === null) {
return null
}
const poppedValue = this.top.value
if (this.top.next !== null) {
this.top = this.top.next
} else {
this.top = null
this.bottom = null
}
this.length--
return this
}
isEmpty() {
if (this.length === 0) {
return true
} else {
return false
}
}
printStack() {
let current = this.top
while (current !== null) {
console.log(current.value)
current = current.next
}
}
}
const myStack = new Stack();
myStack.push("Google")
myStack.push("Udemy")
myStack.push("Youtube")
myStack.printStack()
myStack.pop()
myStack.printStack()
console.log(myStack.peek())
