[Gustly]

async testMethod() {
  let temp = [];
  return await new Promise(resolve => {
    const db = indexedDB.open("EPG");
    db.onsuccess = (event) => {
      let target = event.target.result;
      let tx = target.transaction(["channel"]).objectStore("channel").openCursor();
      tx.onsuccess = (event) => {
        let cursor = event.target.result;
        if (cursor) {
          temp.push(cursor.value);
          cursor.continue();
        } else {
          resolve(temp);
        }
      }
    }
  });
}

var myArr = await testMethod();