Run results for: Inverted map lookup vs. dynamic map lookup

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:84.0) Gecko/20100101 Firefox/84.0

Browser: Firefox 84

Operating system: Windows

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
Inverted map lookup	25179.7 Ops/sec
Dynamic lookup	318.8 Ops/sec

Script Preparation code:

const testMap = {
    test0: '000',
    test1: '001',
    test2: '002',
    test3: '003',
    test4: '004',
    test5: '005',
    test6: '006',
    test7: '007',
    test8: '008',
    test9: '009'
};

// tiny in-place inverting function using array reduce
const testMapInverted = Object.keys(testMap).reduce((acc, val) => {
    acc[testMap[val]] = val;
    return acc;
}, {});

function numberStringInvertedMapLookup(numberString) {
    return testMapInverted.hasOwnProperty(numberString);
}

function numberStringDynamicLookup(numberString) {
    return Object.values(testMap).includes(numberString);
}

function getRandomInt(max) {
  return Math.floor(Math.random() * Math.floor(max));
}

Tests:

Inverted map lookup
for(let i = 0; i < 10000; ++i) { numberStringInvertedMapLookup('00' + getRandomInt(20)); }
Dynamic lookup
for(let i = 0; i < 10000; ++i) { numberStringDynamicLookup('00' + getRandomInt(20)); }

Run results for: Inverted map lookup vs. dynamic map lookup

Inverted map lookup

Dynamic lookup