mathCos_ES5.js

'use strict';

(function () {
    var RADIANS_IN_A_CIRCLE = 2 * Math.PI;
    var ONE_DEGREE = RADIANS_IN_A_CIRCLE / 360;

    var lookup = [];

    for (var index = 0; index < 360; ++index) {
        lookup[index] = Math.cos(index * ONE_DEGREE);
    }

    doOneMillionLookupsAroundWholeCircle();
    doOneMillionLookupsAroundWholeCircle();

    doOneMillionCalculationsAroundWholeCircle();
    doOneMillionCalculationsAroundWholeCircle();

    function doOneMillionLookupsAroundWholeCircle() {
        var start = new Date();
        var result = 0;
        for (
            var count = 0;
            count < 1000000;
            ++count
        ) {
            for (
                var angleDegrees = 0;
                angleDegrees < 360;
                ++angleDegrees
            ) {
                result = result + lookup[angleDegrees];
            }
        }

        var end = new Date();

        var diff = end - start;

        console.log(`Cos lookup (ES5) result: ${result}`);
        console.log(`Cos lookup (ES5) time: ${diff}`);
    }

    function doOneMillionCalculationsAroundWholeCircle() {
        var start = new Date();
        var result = 0;
        for (
            var count = 0;
            count < 1000000;
            ++count
        ) {
            for (
                var angleDegrees = 0;
                angleDegrees < 360;
                ++angleDegrees
            ) {
                result = result + Math.cos(angleDegrees * ONE_DEGREE);
            }
        }

        var end = new Date();

        var diff = end - start;

        console.log(`Math.cos (ES5) result: ${result}`);
        console.log(`Math.cos (ES5) time: ${diff}`);
    }
}());