Test of using TypeScript. See post here: https://www.devbanana.me/static-typing/2021/09/23/typescript-for-statically-typed-javascript.html

index.ts

function getWord(text: string, word: number) {
  if (word < 1) throw new Error('word must be no less than 1');

  const wordIndex = word - 1;

  // https://regex101.com/r/1zDG8a/2
  const words = text.toLowerCase().match(/\w+(?:'\w+)*/g);
  if (words === null) {
    throw new Error('Please provide some text');
  }

  if (wordIndex >= words.length) {
    throw new Error(`Text only has ${words.length} words`);
  }

  return words[wordIndex];
}

console.log(getWord('This is a test.', 2));

tsconfig.json

{
  "compilerOptions": {
    "target": "ES2015",
    "noEmitOnError": true,
    "strict": true
  },
  "files": ["./index.ts"]
}