JSFiddle - React, Tailwind, and code Playground

JavaScript

function testFunc(test) {
    for(var i=0;i<100000000;i++) { i = i+test; }
    };

function testFunc2(test) {
    for(var i=0;i<100000000;i++) { i = i+test; }
    };

var getPerfResults = (function(){
    var timeRecords = {}, xTr = 0, name;
    var setPerfRecords = function(oFn, fnIdentity) {
        timeRecords[fnIdentity] = [];
        return function(){
            var xTime = performance.now();
            var xResult = oFn.apply(this, arguments);
            xTime = performance.now()-xTime;
            timeRecords[fnIdentity].push(xTime);
            return xResult;
            };
        };
    for (name in window) {
        try { window[name]; // Security exception may occur here
        if (typeof window[name] === 'function')
            window[name] = setPerfRecords(window[name], name);
            }
        catch(err) { }
        }
    return function() {
        var resultObj = {}, n, i;
        for(i in timeRecords) {
            if(timeRecords.hasOwnProperty(i)
             && timeRecords[i].length > 0) {
                resultObj[i] = 0; 
                for(n=0;n<timeRecords[i].length;n++) {
                    resultObj[i] = resultObj[i]+timeRecords[i][n];
                    }
                resultObj[i] = resultObj[i]/timeRecords[i].length;
                }
            }
        return resultObj;
        };
    }());

testFunc(1);
testFunc(10);
testFunc(100);
testFunc(1000);
testFunc(10000);
testFunc2(0);

document.body.innerHTML = JSON.stringify(getPerfResults());