What is a Hash Map Data Structure | JavaScript

What is a Hash Map Data Structure | JavaScript

Hash Map is a non-linear data structure in computer science. Hash Maps act like key-value stores and are very efficient at saving and retrieving data.

Hash Maps

  • hash function - converts a key into an index within the hash map's underlying array
  • hash collision - happens when a hash function returns the same index for several different keys
  • assign - saves data to a hash map at a specified by hash function index
  • retrieve - looks up the value in a hash map based on its key
Hash Map Visualization

Data Types & Structures

Hash Maps are generally implemented using Arrays or Arrays of Linked Lists.

Hash Map implementation using an Array of Linked Lists

class HashMap {
  constructor(size = 0) {
    this.hashmap = new Array(size)
      .map(() => new LinkedList());

  hash(key) {}

  assign(key, value) {}

  retrieve(key) {}