mutable.js

// *SMELL*
function mutableData() {
  let name = {
    firstName: "Rafael",
    lastName: "Melo"
  };
  name = `${name.firstName} ${name.lastName}`;
  return name;
}

// *REFACTORED*
function nonMutableData() {
  const name = {
    firstName: "Rafael",
    lastName: "Melo"
  };
  const fullName = `${name.firstName} ${name.lastName}`;
  return fullName;
}