Javascript performance: test performance of two functions

Javascript
function run(fn, count, ...args) {
   const = start = performance.now();
   
   for (let i = 0; i < count; ++i) {
      fn.apply(null, args);
   }

   return performance.now() - start;
}

Javascript
[10, 100, 1000, 10000].forEach( x => {
   console.log("testFunc1", x, run("testFunc1", x, "foo");
   console.log("testFunc2", x, run("testFunc2", x, "foo");
});