Why does my fetch function return undefined? [duplicate]

I'm making a chrome extension where I'm calling the youtube API and using fetch() to do so. I don't understand why I'm getting an undefined variable when I call the function. Here is where I'm calling the function;

document.querySelector("[type=button]").addEventListener("click", function() {    //console.log("this was clicked");    let videoId = document.getElementById('vidUrl').value;    videoId = videoId.substring(videoId.indexOf('=') + 1);    console.log(videoId);    //chrome.runtime.sendMessage({ msg: "startFunc", vidId: videoId});    let request = addToQueue(videoId);    console.log(request);    console.log(request.snippet.title);    let table = document.querySelector(".table");    let row = table.insertRow(table.rows.length);    let title = row.insertCell(0);    let author = row.insertCell(1);    title.innerHTML = request.Data.snippet.title;    author.innerHTML = request.Data.snippet.videoOwnerChannelTitle;})

and this is the function itself;

function addToQueue(vidId){    chrome.identity.getAuthToken({ interactive: true }, function (token) {      //console.log(token);            let fetchString = 'https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&key=xxxxxxxxxxxxxxxxxx'      let post =       {"part": ["snippet"        ],"id": "UC0E5pDp_c2riLV4UhEgynKA","snippet": {"playlistId": "PLu4fFFN_062GzqARIz3gnERiJ8M4GbRcL","position": 1,"resourceId": {"kind": "youtube#video","videoId": vidId            }        }      }      let fetchOptions = {        method: 'POST',        headers: {          Authorization: `Bearer ${token}`,'Content-Type': 'application/json',        },        body: JSON.stringify(post),      }      fetch(fetchString,fetchOptions)        .then((response) => response.json())        .then(function (data) {          console.log(data);          //console.log(typeof data);          //chrome.runtime.sendMessage({Data : data});          return data;      });    })  }

I'm fairly new to javascript and chrome extensions so please forgive me if this is something obvious.