function doit(mode) {

    function make_x_first(x,y) {
        return {x, y};
    }

    function make_y_first(x, y) {
        return {y, x};
    }

    function make_mixed(x, y) {
        if (Math.random() > 0.5) {
            return make_y_first(x, y);
        } else {
            return make_x_first(x, y);
        }
    }

    function make_rand_prefix(x, y) {
        let rando = (Math.random() * (2 ** 32 - 1)) | 0;
        let r = 'random' + rando;
        let o = {[r]: r, x, y};
        return o;
    }

    function make_rand_suffix(x, y) {
        let rando = (Math.random() * (2 ** 32 - 1)) | 0;
        let r = 'random' + rando;
        let o = {x, y, [r]: r};
        return o;
    }

    const million = 1000 * 1000;
    const n = 1 * million;
    const runs = 100 * n;

    function bulk(filler) {
        let a = [];
        for (let i = 0; i < n; i++) {
            a.push(filler(i, i * i));
        }
        return a;
    }

    let funcMap = {
        'x-first': make_x_first,
        'y-first': make_y_first,
        'mixed': make_mixed,
        'rand-prefix': make_rand_prefix,
        'rand-suffix': make_rand_suffix,
    };
    let func = funcMap[mode];
    if (!func) {
        console.log(`Pass as parameter one of:`);
        for (let key of Object.keys(funcMap)) {
            console.log(`  ${key}`);
        }
        process.exit(1);
    }
    const data = bulk(func);

    function time(func) {
        const start = Date.now();
        func();
        const delta = Date.now() - start;
        return delta;
    }

    function report(func) {
        let delta = time(func);
        console.log(`${delta} ms`);
    }

    function demo(dataSet) {
        for (let i = 0; i < 3; i++) {
            console.log(`run ${i+1}`);
            report(() => {
                let sumX = 0, sumY = 0;
                for (let i = 0; i < runs; i++) {
                    let item = dataSet[i % dataSet.length];
                    sumX += item.x;
                    sumY += item.y;
                }
                return {x: sumX, y: sumY};
            });
            console.log(``);
        }
    }

    console.log(`** ${mode}`);
    demo(data);
}

let mode = String(process.argv[2]);
doit(mode);