script.js

const inputBox= document.getElementById('input-box');
const listContainer=document.getElementById('list-checking');

function newTask(){
    if(inputBox.value===''){
        alert('You muust write something');
    }
    else{
        let li=document.createElement('li');
        li.innerHTML=inputBox.value;
        listContainer.appendChild(li);
        let span=document.createElement('span');
        span.innerHTML="\u00d7";
        li.appendChild(span);
    }
    inputBox.value='';
    saveData();
}
listContainer.addEventListener('click',function(e){
if(e.target.tagName==='LI'){
    e.target.classList.toggle('checked');
    saveData()
}
else if(e.target.tagName==='SPAN'){
    e.target.parentElement.remove();
    saveData();
}
},false);

function saveData(){
    localStorage.setItem('data',listContainer.innerHTML);
}
function showData(){
  listContainer.innerHTML=  localStorage.getItem('data')
}
showData();