Min Stack LeetCode solution in JavaScript

1
var MinStack = function () {
2
  this.stack = [];
3
  this.min = [];
4
};
5

6
MinStack.prototype.push = function (val) {
7
  this.stack.push(val);
8

9
  const lastMin = this.min[this.min.length - 1];
10

11
  if (lastMin === undefined || val < lastMin) {
12
    this.min.push(val);
13
  } else {
14
    this.min.push(lastMin);
15
  }
16
};
17

18
MinStack.prototype.pop = function () {
19
  this.stack.pop();
20
  this.min.pop();
21
};
22

23
MinStack.prototype.top = function () {
24
  return this.stack[this.stack.length - 1];
25
};
26

27
MinStack.prototype.getMin = function () {
28
  return this.min[this.min.length - 1];
29
};