var b= age.find(checkAdult);//It will find and return the only first value that is finded greater or equal to 18. var c= ages.findIndex(checkage);//It will find and return the index of first value ...

callbackFn : A function to execute for each element in the array. It should return a truthy value to indicate a matching element has been found, and a falsy value otherwise. The function is called ...