process/helpers.js
function(arr, iterator) {
  var i = arr.length - 1, index = null

  if(i >= 0){
    do {
      if(iterator(arr[i])) {
        index = i
        break
      }
    } while(i--)
  }

  return index
}
function(arr, iterator) {
  var i = arr.length - 1, index = null

  if(i >= 0){
    do {
      if(iterator(arr[i])) {
        index = i
        break
      }
    } while(i--)
  }

  return index
}
function ( arr , iterator ) { var i = arr . length - 1 , index = null if ( i >= 0 ) { do { if ( iterator ( arr [ i ] ) ) { index = i break } } while ( i -- ) } return index }
Returnn the first index of the array matching the iterator
Returnn the first index of the array matching the iterator