script.js

const inputBox = document.getElementById("input-box");
const ctask = document.getElementById("c-task");
const listContainer = document.getElementById("list-container");

function addTask(){
    if(inputBox.value === ''){
        alert("you ust 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()