6.8 Finder Function created by smillaraaq - https://repl.it/HGRh/3

6.8 Finder Function.js

function finderFunction(searchArray, testerFunction){
  for(var i=0;i<searchArray.length;i++){
    if(testerFunction(searchArray[i])){
      return i;
    }
  }
  return -1;
}

function finderFunctionArray(searchArray, testerFunction){
  var evensArray=[];
  for(var i=0;i<searchArray.length;i++){
    if(testerFunction(searchArray[i])){
      evensArray.push(searchArray[i]);
    }
  }
  if(evensArray.length){
    return evensArray;
  }else{
    return -1;
  }
}
var numbers = [1, 3, 5, 64, 7, 12];
var odds = [9, 13, 15, 17];

function isEven(num) { return !(num % 2); };

console.log(finderFunction(numbers, isEven)) // 3
console.log(finderFunction(odds, isEven))   // -1
console.log(finderFunctionArray(numbers, isEven)) // 3
console.log(finderFunctionArray(odds, isEven))   // -1