When I click on the Add Note Button without entering any text, I do not want the local storage to add an empty string, instead I want an alert message to pop up saying “enter a text”. I tried a few ways trying to place alert function at different points, but an ERROR is displayed saying “properties of null can’t be read”. Please suggest some code. Thank you.
[1]: https://i.stack.imgur.c

 console.log("Add Notes");
// If user adds a note, add it to the localStorage
let btnBag = document.getElementById("addBtn");
btnBag.addEventListener("click", function(e) {
  let txtBag = document.getElementById("addTxt");
  let notesBag = localStorage.getItem("notes");
  if (notesBag == null) {
    notesBag = [];
  } else {
    notesBag = JSON.parse(notesBag);
  localStorage.setItem("notes", JSON.stringify(notesBag));
  txtBag.value = "";
  // showAlert();
//Function to display elements located in localStorage
function showNotes(){
  // place the notes array in an element called notesBag
let notesBag = localStorage.getItem("notes");
  if (notesBag == null) {
    objBag = [];
  } else {
    objBag = JSON.parse(notesBag);
  // create a blank string named html
  let html="";
  // For the notesBag(which is parsed and placed into the objBag element) create forEach loop so that each notes stored in array is shown seperateley
  objBag.forEach(function (element,index) {
    html +=`
    <div id="notes" class=" row container-fluid">
            <div class="noteCard mx-2 my-2 card" style="width: 18rem;">
                <div class="card-body">
                    <h5 class="card-title">Note ${index+1}</h5>
                    <p class="card-text">${element}</p>
                    <button id = "${index} onclick = "deleteNote(this.id)" class="btn btn-primary">Delete Note</button>
        </div> `;
    let notesElem = document.getElementById("notes");
    if(objBag.length != 0){
      notesElem.innerHTML = html;
    } else { 
      notesElem.innerHTML = `Add Something for displaying the note`;

  //Delete a note

/* // Function to delete a note
function deleteNote(index) {

  let notes = localStorage.getItem("notes");
  if (notes == null) {
    notesObj = [];
  } else {
    notesObj = JSON.parse(notes);

  notesObj.splice(index, 1);
  localStorage.setItem("notes", JSON.stringify(notesObj));
} */

// let search = document.getElementById('searchTxt');
// search.addEventListener("input", function(){

//     let inputVal = search.value.toLowerCase();
//     // console.log('Input event fired!', inputVal);
//     let noteCards = document.getElementsByClassName('noteCard');
//     Array.from(noteCards).forEach(function(element){
//         let cardTxt = element.getElementsByTagName("p")[0].innerText;
//         if(cardTxt.includes(inputVal)){
//             element.style.display = "block";
//         }
//         else{
//             element.style.display = "none";
//         }
//         // console.log(cardTxt);
//     })
// })

/*Further Features:
1. Add Title
2. Mark a note as Important
3. Separate notes by user
4. Sync and host to web server 
<!DOCTYPE html>
<html lang="en">

    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Practice code</title>
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet"
        integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"
        integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
        .navbar-brand {
            color: red;

    <nav class="navbar navbar-expand-lg  bg-dark ">
        <a class="navbar-brand" href="#">Multiple Notes</a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent"
            aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>

        <div class="collapse navbar-collapse" id="navbarSupportedContent">
            <ul class="navbar-nav mr-auto">
                <li class="nav-item active">
                    <a href="#">Home <span class="sr-only">(current)</span></a>

            <form class="form-inline my-2 my-lg-0">
                <input class="form-control mr-sm-2" id="searchTxt" type="search" placeholder="Search"
                <button class="btn btn-outline-success  my-2 my-sm-0" type="submit">Search
    <div class="container my-3">
        <h1>Take Notes Here</h1>
        <div class="card">
            <div class="card-body">
                <h5 class="card-title">Add Note</h5>
                <div class="form-group">
                    <textarea class="form-control" id="addTxt" rows="3"></textarea>
                <button class="btn btn-primary" id="addBtn" onsubmit="showAlert()">Add Note</button>
        <h1>Your Notes</h1>
        <div id="notes" class=" row container-fluid">
            <!-- <div class="noteCard mx-2 my-2 card" style="width: 18rem;">
                <div class="card-body">
                    <h5 class="card-title">First Note</h5>
                    <p class="card-text"></p>
                    <a href="#" class="btn btn-primary">Delete</a>
            </div> -->

<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"

<script src="harry js files/practice.js"></script>



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