These are array-handling functions that return indexes of items in the array.
value: anything except an object . Returns -1 if value not found.
getFirstIndexOf(value, array); // returns integer
Type-checking version of Array.indexOf(). Change the startingPosition to get something other than the first index of primitive. startingPosition can also be negative to search from the end.
getIndexOfPrimitive(primitive, array, startingPosition = 0) // returns -1 if not found
If primitive isn't found, this returns empty array
getIndexesOfPrimitive(primitive, array) // returns array of integers
If arrayToSearchFor is found in arrayToSearchInside, this returns the index of the first found instance.
getFirstIndexOfArray(arrayToSearchFor, arrayToSearchInside); // returns -1 if not found
if arrayToSearchFor isn't found, this returns empty array
getIndexesOfArray(arrayToSearchFor, arrayToSearchInside); // returns array of integers