Data structure - Stack (javascript)

Stack.js

const Stack = new function() {

  let data = [];

  this.pop = () => data.pop();
  this.push = (el) => data.push(el);
  this.peek = () => data[data.length - 1];
};

Stack.push(1);
Stack.push(2);
console.log(Stack.peek()); // [1, 2]
Stack.pop();
console.log(Stack.peek()); // [1]