switch case worker

let db;
let objectStore

self.onmessage = function(event) {
  switch(event.data) {
    case('init'): {
      let req = indexedDB.open('vips', 1);
      req.onupgradeneeded = function (e) {
        let db = e.target.result;
        objectStore = db.createObjectStore("name", { autoIncrement: true });
        self.postMessage('Successfully upgraded db');
      };
      req.onsuccess = function (e) {
        db = req.result;
      };
      req.onerror = function(e) {
        self.postMessage('error');
      }
    };
    break;

    case('readAll'): {
      readAll();
    };
    break;

    case('add'): {
      add();
    };
    break;
  }
}