IdxHashMap

A JavaScript data structure providing O(1) insertion, deletion, numeric indexing, and key-based lookup at the cost of space. utilizes the pop and swap method for deletion, be careful if strict indexed order matters

Installation

npm install indexed-hash-map

Usage:

const IdxHashMap = require('indexed-hash-map');

const map = new IdxHashMap();

map.set("name", "Ari");
map.set("color", "purple");

console.log(map.get("name"));        // Ari
console.log(map.idx(1));              // purple

// .find is increased to O(1) if given a direct key or index
console.log(map.find("color"));  // purple O(1)

// if .find is still given a callback, then it remains as it's original O(n)
const foundValue = map.find((value) => value === "purple");
console.log(foundValue);  // purple O(n)

// if not present, returns undefined like the normal array method.
console.log(map.find("age")); // undefined 

// includes is increased to O(1) from O(n).
console.log(map.includes("color"));   // true

// indexOfKey is increased to O(1) from O(n)
console.log(map.indexOfKey("color")); // 1

// forEach, map and filter remain their original time complexity of O(n)
map.forEach((val, idx) => console.log(idx, val)); // 0 Ari, 1 purple

const upperCaseValues = map.map(val => val.toUpperCase());
console.log(upperCaseValues); // ["ARI", "PURPLE"]

const filteredMap = map.filter((val) => val !== "Ari");
filteredMap.forEach((val, idx) => console.log(idx, val)); // 0 purple

//since the key is an object, it allows for any combination of the three properties (key, value, idx) to be given in an object as an argument and returned. 
for (const {value, key, idx} of map) {
  console.log(idx, key, value);          //(0, name, Ari), (1, color, purple)
}

map.del("name");

console.log(map.len());               // 1
console.log(map.length)               // 1

Other Usage:

IdxHashMap also allows for 2 arguments to be passed, the key mapped to a node, as well as the index mapped to a node.

If data storage and loading is a factor, you can restore for serialzation by passing the map keys and map indicies.

for more performance optimzation, you can use the first argument to map custom keys from an object, while the second argument would be the pre-allocated array.

There are probably even more uses for this that I am not aware of yet, but will maybe update the readme with more info.

Message me for any questions!