This function is returning undefined and I want it to return the value of the variable final. How can I achieve this?

Question

This function is returning undefined and I want it to return the variable final. How can I achieve this? Please help!!

const getIndex = ()=>{
  let heroName = searchfield.value
  fetch(`https://akabab.github.io/superhero-api/api/all.json`)
  .then(response => response.json())
  .then(json => {
    let result = json.find(item => item.name === `${heroName}`);
    // console.log(result)
    let final = (result.id);
    console.log(final)
  })
  return final
}

This is resulting undefined. I even tried to the final variable global and then do it but still got undefined