script.js

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

inputBox.addEventListener("keypress", function (e) {
    if (e.key === "Enter") {
        addTask();
    }
});

function addTask() {
  if(inputBox.value === "") {
    alert("Please enter something dude!");
  }
  else{
      let li = document.createElement("li");
        li.innerHTML = inputBox.value;
        listContainer.appendChild(li);
        let span = document.createElement("span");
        span.innerHTML = "x";
        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();