javascript – how to get value from promise?

I saved data into AsyncStorage in reactnative project.
then I want to read data from that and filter perioddata with first cell after split.

//save data:
  const storeSelectedfarm = async (value) => {//value is "2:1"
    try {
      await AsyncStorage.setItem("mydata", value);
    } catch (e) {
      // saving error
    }
  };


//my data
let perioddata = (
    { key: "43", masterref: "1", name: "period12" },
    { key: "44", masterref: "1", name: "period13" },
    { key: "45", masterref: "2", name: "period20" },
    { key: "46", masterref: "1", name: "period14" });


//my get data code
{perioddata.filter(function (item) {
                let saveddata = async () =>
                  await AsyncStorage.getItem("mydata")
                    .then(function (result) {
                      return result;
                    })
                    .catch(function (err) {
                      return "2:1";
                    });
                return (
                  item.masterref=== saveddata.split(":")(0).trim()
                );
              })}

error: saveddata.split is not a function. (In ‘saveddata.split(“:”)’, ‘saveddata.split’ is undefined)