dope-map

A wrapper around Map that adds the ability to uses keys of equal but not referential value. This comes with a performance tradeoff (see Benchmarks), so if your dataset is large take that into consideration.

Ships with a hardcoded (dep-free) implementation of fast-json-stable-stringify and xxhashjs as its hashing function. You can supply a different hashing function in DopeMap's config (as long as it returns a string or number).

RoadMap 🚧

1. Enhance interactive demo site (check out the wip here)
2. Native hash for node

Installation

yarn add @johnhaup/dope-map

Usage

import DopeMap from "@johnhaup/dope-map";

const dopeMap = new DopeMap();

const key1 = { foo: "bar", to: "fu" };
const key2 = { foo: "bar", to: "fu" };

dopeMap.set(key1, [1, 2, 3, 4, 5]);
dopeMap.set(key2, "numbers");

console.log(dopeMap.size); // Output: 1
console.log(dopeMap.get(key1)); // Output: "numbers"
console.log(dopeMap.get(key2)); // Output: "numbers" <- Same reference as above
console.log(dopeMap.get({ to: "fu", foo: "bar" })); // Output: "numbers" <- Same reference as above

// Compared to Map
const map = new Map();

map.set(key1, [1, 2, 3, 4, 5]);
map.set(key2, "numbers");

console.log(map.size); // Output: 2
console.log(map.get(key1)); // Output: [1, 2, 3, 4, 5]
console.log(map.get(key2)); // Output: "numbers"
console.log(map.get({ to: "fu", foo: "bar" })); // Output: undefined

API Reference

In addition to standard Map methods

Config

DopeMaps constructor accepts a second config argument.

import DopeMap from "@johnhaup/dope-map";
import hashIt from "hash-it";

const dopeMap = new DopeMap(null, { hashFunction: hashIt });

Property	Type	Description
hashFunction	(key: unknown) => string | number	Custom hashing function for non-primitive keys.

Methods

Method	Return Value
getEntries	Array of [key, value] tuples in order of entry
getKeys	Array of keys in order of entry
getValues	Array of values in order of entry

Benchmarks

Each Dope/Map grows to the iteration size. Averages of method time are below. All times are in milliseconds.

OBJECTS keys

100 iterations

Map	Set	Get	Has	Delete
Map	0.001	0.0	0.0	0.0
DopeMap	0.004 (+0.003)	0.002 (+0.002)	0.001 (+0.001)	0.002 (+0.001)
DopeMap w/hash-it	0.004 (+0.003)	0.002 (+0.002)	0.001 (+0.001)	0.002 (+0.002)
DopeMap V1	0.071 (+0.070)	0.070 (+0.070)	0.067 (+0.067)	0.068 (+0.068)

1,000 iterations

Map	Set	Get	Has	Delete
Map	0.011	0.0	0.001	0.005
DopeMap	0.050 (+0.039)	0.028 (+0.027)	0.016 (+0.015)	0.019 (+0.015)
DopeMap w/hash-it	0.053 (+0.042)	0.033 (+0.033)	0.017 (+0.016)	0.024 (+0.019)
DopeMap V1	0.728 (+0.717)	0.712 (+0.711)	0.703 (+0.703)	0.714 (+0.709)

10,000 iterations

Map	Set	Get	Has	Delete
Map	0.173	0.022	0.033	0.053
DopeMap	0.658 (+0.485)	0.465 (+0.443)	0.192 (+0.158)	0.241 (+0.189)
DopeMap w/hash-it	0.640 (+0.467)	0.487 (+0.465)	0.192 (+0.158)	0.286 (+0.233)
DopeMap V1	7.6 (+7.4)	7.4 (+7.4)	6.9 (+6.9)	7.0 (+7.0)

100,000 iterations

Map	Set	Get	Has	Delete
Map	1.7	1.5	1.4	0.587
DopeMap	7.0 (+5.3)	5.2 (+3.7)	4.7 (+3.3)	2.4 (+1.8)
DopeMap w/hash-it	8.0 (+6.3)	6.9 (+5.3)	5.3 (+3.9)	2.7 (+2.1)
DopeMap V1	89.6 (+87.9)	84.2 (+82.7)	83.1 (+81.7)	73.4 (+72.8)

PRIMITIVES keys

100 iterations

Map	Set	Get	Has	Delete
Map	0.001	0.0	0.0	0.0
DopeMap	0.002 (+0.002)	0.001 (+0.001)	0.0	0.001
DopeMap w/hash-it	0.002 (+0.002)	0.001 (+0.001)	0.0	0.001
DopeMap V1	0.002 (+0.001)	0.001 (+0.001)	0.001 (+0.001)	0.001

1,000 iterations

Map	Set	Get	Has	Delete
Map	0.012	0.001	0.001	0.005
DopeMap	0.032 (+0.021)	0.013 (+0.012)	0.003 (+0.003)	0.006 (+0.001)
DopeMap w/hash-it	0.033 (+0.021)	0.013 (+0.012)	0.003 (+0.003)	0.006 (+0.001)
DopeMap V1	0.030 (+0.018)	0.020 (+0.019)	0.009 (+0.008)	0.011 (+0.006)

10,000 iterations

Map	Set	Get	Has	Delete
Map	0.204	0.022	0.022	0.051
DopeMap	0.378 (+0.174)	0.195 (+0.173)	0.028 (+0.006)	0.059 (+0.008)
DopeMap w/hash-it	0.378 (+0.174)	0.194 (+0.173)	0.029 (+0.007)	0.061 (+0.010)
DopeMap V1	0.334 (+0.130)	0.251 (+0.229)	0.071 (+0.049)	0.102 (+0.051)

100,000 iterations

Map	Set	Get	Has	Delete
Map	2.7	1.0	1.0	0.560
DopeMap	5.4 (+2.7)	3.1 (+2.0)	2.9 (+1.9)	0.609 (+0.049)
DopeMap w/hash-it	5.7 (+2.9)	3.1 (+2.1)	3.0 (+2.0)	0.612 (+0.052)
DopeMap V1	4.5 (+1.8)	3.4 (+2.3)	1.8 (+0.777)	1.1 (+0.504)