Higher-order function

//Not fully understood yet
const checkThatTwoPlusTwoEqualsFourAMillionTimes = () => {
  for(let i = 1; i <= 1000000; i++) {
    if ( (2 + 2) != 4) {
      console.log('Something has gone very wrong :( ');
    }
  }
};

const addTwo = num => num + 2;

const timeFuncRuntime = funcParameter => {
  let t1 = Date.now();
  funcParameter();
  let t2 = Date.now();
  return t2 - t1;
};


let time2p2 = timeFuncRuntime(checkThatTwoPlusTwoEqualsFourAMillionTimes);

//Higher-order function that has two parameters: a function and a value.
const checkConsistentOutput = (func,val) => {
    let firstTry = func(val);
    let secondTry = func(val);
    if (firstTry === secondTry) {
        return firstTry;
    } else {
        return 'This function returned inconsistent results';
    }
}

console.log(checkConsistentOutput(addTwo, 3));  //pass the function of addTwo but not invoke it