const flags = {
  READ:    0b0001,
  WRITE:   0b0010,
  EXECUTE: 0b0100,
  DELETE:  0b1000,
};

const userPermissions  = flags.READ | flags.WRITE | flags.EXECUTE;
const adminPermissions = userPermissions | flags.DELETE;

const canDelete  = (adminPermissions & flags.DELETE)  !== 0;
const canExecute = (userPermissions  & flags.EXECUTE) !== 0;
const readOnly   = userPermissions   ^ flags.WRITE;

console.log(canDelete, canExecute, readOnly, adminPermissions >> 1);