JS Benchmark: test performance of Set()

js_set_benchmark.js

function test(size, iterations) {

    let data_array = [];
    let data_obj = {};

    for (let i = 0; i < size; i++) {
        let rnd = Math.floor(Math.random() * size * 10);
        data_array.push(rnd);
        data_obj[rnd] = true;
    }

    let data_set = new Set(data_array);

    let t = performance.now();
    for (let j = 0; j < iterations; j++) {
        let x = data_array.indexOf(j) !== -1;
    }
    let t1 = performance.now() - t;

    t = performance.now();
    for (let j = 0; j < iterations; j++) {
        let x = data_obj[j];
    }
    let t2 = performance.now() - t;

    t = performance.now();
    for (let j = 0; j < iterations; j++) {
        let x = data_set.has(j);
    }
    let t3 = performance.now() - t;

    console.log([size, iterations, t1/1000, t2/1000, t3/1000].join(", "));
}

console.log("# Array Size, Iterations, in array, in object, in set");
for (let i = 1; i <= 10000; i *= 10) {
    test(i, 100000)
}

I'm surprised: set.has() is a bit faster than object[key]
Tested in Node.js 10 and Chrome 78

# Array Size, Iterations, in array, in object, in set
1, 100000, 0.004294999991543591, 0.0018899999558925629, 0.0028300000121816993
10, 100000, 0.0055049999500624835, 0.00004499999340623617, 0.001445000001695007
100, 100000, 0.014035000000149012, 0.003824999963399023, 0.0015850000199861825
1000, 100000, 0.08825999998953193, 0.0030350000015459955, 0.0015300000086426735
10000, 100000, 0.8473499999963678, 0.005385000025853515, 0.0016049999976530671