80's Kids #7: She's a Small Wonder.js

/*
Description:
Vicky is quite the small wonder. Most people don't even realize she's not a real girl, but a robot living amongst us. Sure, if you stick around her home for a while you might see her creator open up her back and make a few tweaks and even see her recharge in the closet instead of sleeping in a bed.

In this kata, we're going to help Vicky keep track of the words she's learning.

Write a function, learnWord(word) which is a method of the Robot object. The function should report back whether the word is now stored, or if she already knew the word.

Example:

var vicky = new Robot();
vicky.learnWord('hello') -> 'Thank you for teaching me hello'
vicky.learnWord('abc') -> 'Thank you for teaching me abc'
vicky.learnWord('hello') -> 'I already know the word hello'
vicky.learnWord('wow!') -> 'I do not understand the input'
Robot vicky = new Robot();
vicky.learnWord("hello") -> "Thank you for teaching me hello"
vicky.learnWord("abc") -> "Thank you for teaching me abc"
vicky.learnWord("hello") -> "I already know the word hello"
vicky.learnWord("wow!") -> "I do not understand the input"
Case shouldn't matter. Only alpha characters are valid. There's also a little trick here. Enjoy!
*/
function Robot() {
  this.arr =['i', 'already', 'know', 'the', 'word','thank', 'you', 'for','me','teaching','understand']
}

Robot.prototype.learnWord = function(word) {
  if (/\W|\d|\s/i.test(word)||!word) return "I do not understand the input"
  if (!this.arr.includes(word.toLowerCase())){
  this.arr.push(word.toLowerCase())
  return `Thank you for teaching me ${word}`
  }else
  return `I already know the word ${word}`
}