Challenge: Iterator Pattern

In this challenge, you have to implement the iterator pattern to solve the given problem.

We'll cover the following

Problem statement

In this challenge, you have to reverse iterate a simple hashmap and display its key values.

You need to implement the reverseIterate function that accepts the hashmap, items, and displays the key values in reverse. To reverse iterate, make use of the ReverseIterator class. It contains the following functions:

  • haprevElement: checks if there is a previous element.

  • last: returns the last key value in the map.

  • previous: returns the previous key value in the map.

Apart from the functions mentioned above, you also need to define its constructor.

Input

Calling reverseIterate function on a simple hashmap

Output

Hashmap’s values are displayed in reverse order

Sample input

reverseIterate({'name': 'Anne', 'age': '23', 'gender': 'Female', 'Occupation': 'Engineer'})

Sample output

"Engineer"
"Female"
"23"
"Anne"

Challenge #

Take a close look and design a step-by-step solution before jumping on to the implementation. This problem is designed for your practice, so try to solve it on your own first. If you get stuck, you can always refer to the solution provided. Good Luck!

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class ReverseIterator {
  //define-your-reverse-iterator-here
  hasprevElement(){}
  last(){}
  previous(){}
}
function reverseIterate(items){
  //write-your-code-here
  //to display the values of keys
  //in items in reverse 
  console.log(items)
}

Let’s discuss the solution in the next lesson.