Double all the vocals on an array of string characters

vowelDoubler.js

var vowelDoubler = (array) => {
  for (var i = 0; i < array.length; i++) {
    if (array[i] === 'a' || array[i] === 'e' || array[i] === 'i' || array[i] === 'o' || array[i] === 'u') {
      array.splice(i, 0, array[i])
      i++
    }
  }
  return array;
}