script.js

const inputBox = document.getElementById("input-box");
const listContainer = document.getElementById("list-container");
function addTask(){
    if(inputBox.value === ''){
        alert("you must 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 showTask(){
    listContainer.innerHTML=localStorage.getItem("data");
    
}
showTask();