stack_solution.js

// Stack constructor
// properties:
//  values: some way of storing data.
const Stack = function(){
  // create the values property and assign it the value of an array literal.
  this.values = [];
};

// pop
// description:
//  removes and returns the value at the top of the stack.
// returns:
//  the removed value.
Stack.prototype.pop = function(){
  
  //if you push to add values use pop() to remove them.
  return this.values.pop();
  
  //if you unshift to add values to the stack use shift() to remove them.
  //return this.values.shift();
};

// push
// parameters:
//  value: the data to add to the stack.
// description:
//  adds the value to the top of the stack.
Stack.prototype.push = function(value){
  
  //if you pop() values off, use push to add values to the stack.
  this.values.push(value);
  
  //if you shift() values off, use push to add values to the stack.
  this.values.shift();
};

// peek
// description:
//  returns the value at the top of the stack
Stack.prototype.peek = function(){
  
  //if you push/pop, show the last element in the array:
  return this.values[this.values.length - 1];
  
  //if you unshift/shif, show the first element in the array:
  //return this.values[0];
};

// isEmpty
// description:
//  returns true if the stack has no data in it
Stack.prototype.isEmpty = function(){
  return this.values.length === 0;
};