Why i have to get item from local storage before even storing it?

Why in this code I am getting an item from local storage first even before storing it

let addnote = document.getElementById("addbtn");
addnote.addEventListener("click", saveNote );
let message = document.getElementById("notes2");
function saveNote() {
    let TXT = document.getElementById("addtxt");
    let note = localStorage.getItem("notes");
    console.log("save");
    if(note == 0){
        noteData2 = [];
    }
    else{
        noteData2 = JSON.parse(note);
    }
    noteData.push(TXT.value);
    localStorage.setItem("notes", JSON.stringify(noteData));
    TXT.value = "";
};

Thanks