Run results for: Map keyed by String or Number

Comparing different methods of looking up values keyed by a mixture of string and number keys, for a small number of entries. Used to make decisions about how to cache reverse enum key lookups in ts-enum-util: https://github.com/UselessPickles/ts-enum-util

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36

Browser: Chrome 63

Operating system: Windows

Device Platform: Other

Date tested: 2025 years ago

Test name	Executions per second
Polyfill Map by Value	1358034.0 Ops/sec
Native Map by Value	1380446.0 Ops/sec
Native Map by String	830841.5 Ops/sec
Object by String	844835.7 Ops/sec

Script Preparation code:

function SlowMap() {
  this._keys = [];
  this._values = [];
}

SlowMap.prototype = {
  set: function(key, value) {
    const index = this._keys.indexOf(key);
    if (index !== -1) {
      this._values[index] = value;
    } else {
      this._keys.push(key);
      this._values.push(value);
    }
  },
  
  get: function(key) {
    const index = this._keys.indexOf(key);
    if (index !== -1) {
      return this._values[index];
    } else {
      return undefined;
    }
  }
};

var VALUE_COUNT = 10;
var VALUES = [];

var slowMapByValue = new SlowMap();
var nativeMapByValue = new Map();
var nativeMapByString = new Map();
var objectMapByString = {};

function createStringKey(value) {
  // Need to include type info in key to avoid collisions between similar string and number values.
  return (typeof value) + value;
}

for (let i = 0; i < VALUE_COUNT; ++i) {
  var value = (i % 2) ? i : "value_" + i;
  
  VALUES.push(value);
  slowMapByValue.set(value, i);
  nativeMapByValue.set(value, i);
  nativeMapByString.set(createStringKey(value), i);
  objectMapByString[createStringKey(value)] = i;
}

var testLoopCount = 0;

Tests:

Polyfill Map by Value
const result = slowMapByValue.get(VALUES[testLoopCount++ % VALUE_COUNT]);
Native Map by Value
const result = nativeMapByValue.get(VALUES[testLoopCount++ % VALUE_COUNT]);
Native Map by String
const result = nativeMapByString.get(createStringKey(VALUES[testLoopCount++ % VALUE_COUNT]));
Object by String
const result = objectMapByString[createStringKey(VALUES[testLoopCount++ % VALUE_COUNT])]

Run results for: Map keyed by String or Number

Comparing different methods of looking up values keyed by a mixture of string and number keys, for a small number of entries. Used to make decisions about how to cache reverse enum key lookups in ts-enum-util: https://github.com/UselessPickles/ts-enum-util

Polyfill Map by Value

Native Map by Value

Native Map by String

Object by String