Double Vowels

solution.js

// THE PROBLEM
// ----------------------------------
// https://gist.github.com/tim-hr/3bae7341ca7e566748c13726964d8535

// I: 1 array of 1 char per index
// O: 1 array like the Inut but with each vowel duplicated
// C: No add'l data structures. O(n)
// E: None yet

// PLAN
// ----------------------------------
// For each index, check if vowel
	// If the char is a vowel,
  	// Insert the same char before itself
// Return array

// I don't think this is linear time complexity :(

function doubleVowels (array) {
	array.forEach((char, index) => {
  	if (isVowel(char)) {
    	array = duplicateBefore(index, array)
    }
  })
  return array
}

function duplicateBefore (index, array) {
	array.splice(index, 0, array[index]);
  return array
}

function isVowel (char) {
  return ['a', 'e', 'i', 'o', 'u'].includes(char)
}

// TEST HELPERS
// ----------------------------------
function arrayComparison (target, source, result, description) {
	const actual = target
  const expected = source
	_.isEqual(expected, actual) === result
    ? console.log(`PASS: ${description}`) 
    : console.error(`FAIL: ${description}. Expected ${expected} but got ${actual}`) 
}

function willDetectVowel (letter, expected, description) {
	const actual = isVowel(letter)
	isVowel(expected) === isVowel(actual)
  	? console.log(`PASS: ${description}`) 
    : console.error(`FAIL: ${description}. Expected ${expected} but got ${actual}`)
}

function willDoubleVowels (input, expected, result, description) {
	const actual = doubleVowels(input)
	_.isEqual(expected, actual) === result
    ? console.log(`PASS: ${description}`) 
    : console.error(`FAIL: ${description}. Expected ${expected} but got ${actual}`) 
}

// TESTS
// ----------------------------------
willDetectVowel('a', true, `It should find 'a' to be a vowel`)

willDetectVowel('b', false, `It should notfind 'b' to be a vowel`)

arrayComparison([1], [1], true, 'It should detect one and one are equal')

arrayComparison([1], [2], false, 'It should detect one and two are not equal')

willDoubleVowels(['a'], ['a', 'a'], true, `It should double an array of 1 vowel`)

willDoubleVowels(['a', 'b'], ['a', 'a', 'b'], false, `It should double an array with vowel and consonant`)

willDoubleVowels(['b'], ['b'], true, `It should return same array if no vowels`)