JavaScript Design Patterns for Coding Interviews/

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Challenge: Solution Review

Challenge: Solution Review

This lesson will explain the solution to the problem from the previous coding challenge.

We'll cover the following...

Solution #

Node.js
class ReverseIterator {
  constructor(elements) {
	    this.keys = Object.keys(elements)
      this.index = this.keys.length - 1
      this.elements = elements
   }
  hasprevElement() {
    return this.index >=0
  }
  last(){
	  this.index = this.keys.length - 1 
	  return this.elements[this.keys[this.index]]
  }
  previous(){
    if(this.index >= 0){
      return  this.elements[this.keys[--this.index]]	  	
    }else{
      return null
    }
	
  }
}
function reverseIterate(items){
    var iter = new ReverseIterator(items)
    
    for(var i = iter.last();iter.hasprevElement(); i = iter.previous()){
		  console.log(i)
    }	    
}
reverseIterate({'name': 'Anne', 'age': '23', 'gender': 'Female', 'Occupation': 'Engineer'})

Explanation

In the code above, we defined a ReverseIterator class that initializes the following properties:

  • keys: all the keys of the hashmap are accessed using Object.keys and stored in this property

  • index: keeps track of keys in the hashmap

  • elements: stores the hashmap ...