benchmark various for loop implementations

index.js

"use strict";

(function (factory) {
    if (typeof Benchmark !== "undefined") {
        factory(Benchmark);
    } else {
        factory(require("benchmark"));
    }
})(function (Benchmark) {
    var suite = new Benchmark.Suite;

    Benchmark.prototype.setup = function () {
        var i,
            value,
            length,
            valuesTen = [],
            valuesHundred = [],
            valuesThousand = [],
            valuesTenThousand = [],
            sum = 0;


        for (i = 0; i < 10000; i++) {
            if (i < 10) {
                valuesTen.push(i);
            }
            if (i < 100) {
                valuesHundred.push(i);
            }
            if (i < 1000) {
                valuesThousand.push(i);
            }
            if (i < 10000) {
                valuesTenThousand.push(i);
            }
        }

        function add(val) {
            sum += val;
        }
    };


    suite.add("values.forEach(add); 10", function () {
        valuesTen.forEach(add);
    });
    suite.add("values.forEach(add); 100", function () {
        valuesHundred.forEach(add);
    });
    suite.add("values.forEach(add); 1,000", function () {
        valuesThousand.forEach(add);
    });
    suite.add("values.forEach(add); 1,0000", function () {
        valuesTenThousand.forEach(add);
    });

    suite.add("for (i = 0; i < values.length; i++) 10 {", function () {
        for (i = 0; i < valuesTen.length; i++) {
            sum += valuesTen[i];
        }
    });
    suite.add("for (i = 0; i < values.length; i++) 100 {", function () {
        for (i = 0; i < valuesHundred.length; i++) {
            sum += valuesHundred[i];
        }
    });
    suite.add("for (i = 0; i < values.length; i++) 1,000 {", function () {
        for (i = 0; i < valuesThousand.length; i++) {
            sum += valuesThousand[i];
        }
    });
    suite.add("for (i = 0; i < values.length; i++) 10,000 {", function () {
        for (i = 0; i < valuesTenThousand.length; i++) {
            sum += valuesTenThousand[i];
        }
    });

    suite.add("for (value of values) 10 {", function () {
        for (value of valuesTen) {
            sum += value;
        }
    });
    suite.add("for (value of values) 100 {", function () {
        for (value of valuesHundred) {
            sum += value;
        }
    });
    suite.add("for (value of values) 1,000 {", function () {
        for (value of valuesThousand) {
            sum += value;
        }
    });
    suite.add("for (value of values) 10,000 {", function () {
        for (value of valuesTenThousand) {
            sum += value;
        }
    });

    suite.on("cycle", function (evt) {
        console.log(" - " + evt.target);
    });

    suite.on('error', function (...args) {
        console.log(...args);
    });

    suite.on("complete", function (evt) {
        console.log(new Array(30).join("-"));

        var results = evt.currentTarget.sort(function (a, b) {
            return b.hz - a.hz;
        });

        results.forEach(function (item, idx) {
            console.log((idx + 1) + ". " + item);
        });
    });

    console.log("for-of loop vs forEach");
    console.log(new Array(30).join("-"));
    suite.run();
});

This benchmarks various array sizes and different loop types. Thanks to this gist for the baseline of this test.

Here are the results running against node 10, 12, and 14 on my windows 10 device. In all cases but one back on node 10, the for(var i loop is fastest, followed closely by for of, then trailing behind is Array.forEach.