//Convert a string to spinal case (all-lowercase-words-joined-by-dashes).

function spinalCase(str) {
  // Split string into an array of strings by capital letters, underscores or spaces
  // Rejoin array into one string separated by dashes
  // Convert entire string to lower case
  return str.split(/(?=[A-Z])|_|\s/).join("-").toLowerCase();;
}

spinalCase('This Is Spinal Tap');
spinalCase("thisIsSpinalTap");
spinalCase("The_Andy_Griffith_Show");
spinalCase("Teletubbies say Eh-oh");
spinalCase("AllThe-small Things");