How to add a task to local storage when it's added to the list when we click add button so that when a page is loaded the new task does not disappear. I tried in a list function in javascript but it didn't work. I tried using local storage setitem and getitem and then appending them to the list.
localStorage.setItem("uls",list);
var bvc=localStorage.getItem("uls");
document.getElementsByTagName("ul")[0].appendChild(bvc);
        function incomplete() {
  
            let checkboxes = document.querySelectorAll(".checkb");
        for (let i = 0; i < checkboxes.length; i++) {
            if (checkboxes[i].checked) {
              if (checkboxes[i].parentElement)
                checkboxes[i].parentElement.parentElement.style.display = "none";
            }
        }
    }
function addlist (){
    let newText=document.getElementById("input").value;
  var list=  document.createElement("li");
  list.id="lio";
    list.innerText=newText;
 
    
var radio=document.createElement("input");
if(newText!=""){
radio.type="checkbox";
radio.className="checkb";
let sp=  document.createElement("span");
sp.appendChild(radio);
var trash=document.createElement("button");
trash.id="trashed";
trash.className="delete-trash";
trash.innerHTML='<i class="fa fa-trash-o" ></i>';
list.appendChild(sp);
list.appendChild(trash);
localStorage.setItem("uls",list);
var bvc=localStorage.getItem("uls");
document.getElementsByTagName("ul")[0].appendChild(bvc);
}
trash.onclick=function(){
    if  (confirm("Do you really want to delete this?")){
    var value=trash.parentElement;
value.remove();
  }
};
document.getElementById("input").value = "";
}
function deletes(element){
  if  (confirm("Do you really want to delete this?")){
    var value=element.parentElement.parentElement;
value.remove();
  }
}
function allTasks(){
    let checkboxes=document.querySelectorAll(".checkb");
    for (let i = 0; i < checkboxes.length; i++) {
            if (checkboxes[i].checked || !(checkboxes[i].checked)) {
                checkboxes[i].parentElement.parentElement.style.display = "inline-block";
            }
        }
 
} body {
            font-family: "Rubik";
            overflow:none;
            background-image: url("purple\ back.avif");
            background-repeat: no-repeat;
            background-size: cover;
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            overflow:auto;
        }
    
        .container {
            height: 910px;
            display: flex;
         justify-content: center;
         
         z-index: 1;
        }
    
        .page {
            border: 2px solid #333; 
            background-color: #f0f0f0; 
            padding: 20px; 
          
        }
    
        .box {
            overflow-y: auto;
            border: 3px solid #333; 
            height: 600px;
            width: 500px;
            border-radius: 30px;
            margin-top:25px;
            background-color: white;
        }
    
        #heading {
            text-align: left;
            font-weight: bold;
            color: #333;
          
            padding: 10px; 
            margin: 0; 
        }
    
        .content {
            display: flex;
            flex-direction: column;
            justify-content: space-between;
        }
    
        .btn {
            padding: 8px 16px;
            background-color: #007bff; 
            color: #fff; 
            border: none;
            cursor: pointer;
            margin-right: 10px; 
        }
    
        .buttons {
            margin-left: 7em;
     
       
        
        }
    
    
    
        li {
        
            width: 100%;
            height: 35px;
            background-color: #fff; 
            margin-top: 5px; 
            padding: 5px; 
            display: inline-block;
            margin-left: -35px;
            margin-bottom: 20px;
        }
    
        #trashed {
            font-size: 20px;
            color: red;
        }
    
        .delete-trash {
            margin: 2px;
            background-color: #fff; 
            color: red;
            border: none;
            float: right;
            cursor: pointer;
        }
        .addTask{
            
           margin-top: 15px;
            display: flex;
            flex-wrap: wrap;
            margin-left: 10px;
        
        }
        .addT{
            height: 35px;
            border-radius: 20px;
            width: 65%;
            margin-left: 40px;
        }
        .add{
            height: 40  px;
            border-radius: 20px;
            width: 100px;
            position: relative;
            right: 45px;
            background-color: rgb(248, 124, 79);
            color: white;
            
        }
        .radio{
            margin: 4px;
        }
        .checkb{
            float: left;
            margin-right: 4px;
        }
       @media screen and (max-width:480px){
        .box{
            width: 300px;
            height: 600px;
        }
        .add{
            height:35px;
            position: relative;
            left: 85px;
            top: 10px;
        }
        .buttons{
margin-left: 2rem;
        }
        .btn{
            margin: 2px;
            
        }
       } <!DOCTYPE html>
<html lang="en">
<head>
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=Rubik&display=swap" rel="stylesheet">
 <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>To Do List1</title>
</head>
<body>
    <div class="container">
        <div class="box">
        
            <h1 id="heading">To Do List</h1>
            <br>
            <div class="addTask"><input type="text" class="addT" id="input" placeholder="Add your tasks">
            <button class="add"  onclick="addlist()">ADD</button></div>
            
        
        <div class="content" id="content">
            
            
                <br><br>
            <ul>
                <li > <span class="radio"><input type="checkbox"  class="checkb"></span>Learn the basic structure and tags for creating web pages. <span class="delete2"><button class="delete-trash" onclick="deletes(this)"><i class="fa fa-trash-o" style="font-size:20px;color:red"></i></button></span></li>
                <li ><span class="radio"><input type="checkbox"name="check"  class="checkb"></span>Study styling and layout techniques to make.  <span class="delete2"><button class="delete-trash" onclick="deletes(this)"><i class="fa fa-trash-o" style="font-size:20px;color:red"></i></button></span></li>
                <li ><span class="radio"><input type="checkbox" name="check" class="checkb"></span> Understand the fundamentals of programming .   <span class="delete2"><button class="delete-trash"  onclick="deletes(this)"><i class="fa fa-trash-o" style="font-size:20px;color:red"></i></button></span></li>
                <li ><span class="radio"><input type="checkbox" name="check"  class="checkb"></span> Create websites that adapt to different screen sizes. <span class="delete2"><button class="delete-trash"  onclick="deletes(this)"><i class="fa fa-trash-o" style="font-size:20px;color:red"></i></button></span></li>
            </ul>
         <!--  MAIN BUTTONS ADD DELETE-->
         <div class="buttons">
           
            <button class="btn"    onclick="allTasks()">ALL TASKS</button>
            <button class="btn" onclick="incomplete()" >INCOMPLETE TASKS</button>
            </div>
        </div>
        </div>
       
        </div>
      </body>
</html> 
    