Tasks restores after deletion

I added 3 tasks, for example “Task1”, “Task2”, “Task3”, then removed one of them. Pushing on recycle bin, the task will be removed, but when I add new task “Task4”, removed task will be restored too.

How to do I fix it? Please add an explanation if possible?

'use strict';

const headerInput = document.querySelector('.header-input');
const todoControl = document.querySelector('.todo-control');
const todoList = document.querySelector('.todo-list');
const todoCompleted = document.querySelector('.todo-completed');

const todoData = [];

const render = function() {
    todoList.textContent = '';
    todoCompleted.textContent = '';

    todoData.forEach(function(item){
        const li = document.createElement('li');
        li.classList.add('todo-item');
        li.innerHTML = '<span class="text-todo">' + item.value + '</span>' + 
                        '<div class="todo-buttons">' +
                            '<button class="todo-remove"></button>' +
                            '<button class="todo-complete"></button>' +
                        '</div>';

        if(item.completed){
            todoCompleted.append(li);
        } else {
            todoList.append(li);
        }

        const btnTodoCompleted = li.querySelector('.todo-complete');

        btnTodoCompleted.addEventListener('click', function(){
            item.completed = !item.completed;
            render();
        })

        const btnRemove = li.querySelector('.todo-remove');

        btnRemove.addEventListener('click', function(){
            li.remove();
        });
    });

};


todoControl.addEventListener('submit', function(event){
    event.preventDefault();

    const newTodo = {
        value: headerInput.value,
        completed: false
    };

    todoData.push(newTodo)

    render();
});

render();

Answer

When you create a new task, you add a record to the array:

todoData.push(newTodo)

But when you delete a task, you don’t modify the array. You just delete the <li> element from the page:

li.remove();

So the next time render() is called, it will re-render the list from the array which still contains the “deleted” record.

Instead of deleting the <li> element, delete the record from the array and re-invoke render():

btnRemove.addEventListener('click', function(){
    // re-assign the array to a filtered version of itself
    todoData = todoData.filter(function (i) {
        // only return records which don't match the current record
        return item.value !== i.value;
    });
    // re-render the list
    render();
});