caps first letter in str

capsFirstLetter.js

function capsFirstLetter(str) {
  if (typeof str !== "string") {
    throw new Error("param `str` must be a string!");
  }
  const firstLetterCaps = str[0].toUpperCase();
  const restOfString = str.slice(1);
  return firstLetterCaps + restOfString;
}

const myStr = "something";
const results = capsFirstLetter(myStr)
console.log(results)