Javascript constructor for testing function execution speeds

speedTest.js

function speedTest(testImplement, testParams, repetitions = 10000) {
  // code to be tested
  this.testImplement = testImplement;
  // parameters needed for code
  this.testParams = testParams;
  // optional number of reps; higher = better average
  this.repetitions = repetitions;
  this.average = 0;
}

// add methods to Prototype for better preformance
speedTest.prototype = {
  startTest: () => {
    let beginTime, endTime, sumTimes = 0;
    for (let i = 0, x = this.repetitions; i < x; i++) {
      beginTime = +new Date();
      this.testImplement( this.testParams );
      endTime = +new Date();
      sumTimes += endTime - beginTime;
    }
    this.average = sumTimes / this.repetitions;
    return console.log('Average executions across ' + this.repetitions + ': ' + this.average);
  },
};

To use, create a new test:

function exampleFunction (param1, param2) {
  console.log(param1 + " " + param2 );
}
var exampleTest = new SpeedTest(exampleFunction, ["foo", "bar"], 20000)

Then call the startTest method:

exampleTest.startTest()