Dodanie zadania do todo listy

Mam pewien problem. Otóż jak sprawdzić czy użytkownik wprowadził już jakieś zadanie i uniemożliwić mu wprowadzenie ponownie tego samego zadania.

if(!juzIstniejeTakieZadanie(zadanie))
    dodaj(zadanie);

pokaż kod? to można zrobić na wiele sposobów.. Musisz mieć coś unikatowego. Jakieś id, lub title jako rodzaj id. Które musi być unikatowe.

const taskInput = document.getElementById('enter-task');
const addTaskBtn = document.querySelector('[data-submit-task]');
const toDoContainer = document.querySelector('[data-todo]');

addTaskBtn.addEventListener('click', addTask);
function addTask() {
	if (taskInput.value == '') {
		return;
	}
	

	const taskContainer = document.createElement('div');
	
	taskContainer.classList.add('task-container');
	taskContainer.innerHTML = `<input type="checkbox" data-complete><p class="task-date">Data utworzenia: <span data-task-date>${getDate()}</span></p><div class="content-edit"><span data-task-title>${taskInput.value}</span><button type="button" data-edit>Edycja</button></div><button type="button" data-delete>X</button>`;

	

	const completeTaskBtn = taskContainer.querySelector('[data-complete]');
	const deleteTaskBtn = taskContainer.querySelector('[data-delete]');
	const editTaskBtn = taskContainer.querySelector('[data-edit]');

	completeTaskBtn.addEventListener('click', markAsDone);
	deleteTaskBtn.addEventListener('click', deleteTask);
	editTaskBtn.addEventListener('click', editTask);

	toDoContainer.appendChild(taskContainer);
}
function markAsDone() {
	const taskTitle = this.parentNode.querySelector('[data-task-title]');
	if (this.checked) {
		taskTitle.style.textDecoration = 'line-through';
		return;
	}
	taskTitle.style.textDecoration = 'none';
}

function deleteTask() {
	toDoContainer.removeChild(this.parentNode);
}

function editTask() {
	const taskContainer = this.parentNode.parentNode;
	if (taskContainer.contains(taskContainer.querySelector('.task-edit-container'))) {
		return;
	}

	const currentTaskTitle = this.previousElementSibling;

	const editTaskContainer = document.createElement('div');
	editTaskContainer.classList.add('task-edit-container');
	editTaskContainer.innerHTML = `<label>Wprowadź treść zadania</label><input type="text"><button type="button">OK</button>`;


	const submitTitleBtn = editTaskContainer.querySelector('button');		
	submitTitleBtn.addEventListener('click', function() {		
		const newTitle = editTaskContainer.querySelector('input').value;
		if(newTitle == '') {
			return;
		}

		const currentDate = document.querySelector('[data-task-date]');
		currentDate.innerHTML = `<p class="task-date">Data modyfikacji: <span data-task-date>${getDate()}</span></p>`;

		currentTaskTitle.innerHTML = newTitle;			
		taskContainer.removeChild(editTaskContainer);
	});

	taskContainer.appendChild(editTaskContainer);
}

function getDate() {
	let date = new Date();
	let day = date.getDate();
	let monthIndex = date.getMonth();
	let year = date.getFullYear();
	let hours = date.getHours();
	let minutes = date.getMinutes();
	let seconds = date.getSeconds();

	if(minutes < 10) minutes =  "0" + minutes;
	if(seconds < 10) seconds = "0" + seconds;
	const months = ["Styczeń", "Luty", "Marzec", "Kwiecień", "Maj", "Czerwiec", "Lipiec", "Sierpień", "Wrzesień", "Październik", "Listopad", "Grudzień"];
	return `${day} ${months[monthIndex]} ${year} ${hours} : ${minutes} : ${seconds}`; 
}

coś takiego

  const titleExists = !!document.querySelector(`[data-key=${taskInput.value}]`);

    if (taskInput.value == '' || titleExists) {
        return;
    }

    const taskContainer = document.createElement('div');

    taskContainer.classList.add('task-container');
    taskContainer.innerHTML = `<input type="checkbox" data-complete>
    <p class="task-date">Data utworzenia: 
    <span data-task-date>${getDate()}</span></p><div class="content-edit">
    <span data-task-title>${taskInput.value}</span><button type="button" data-edit data-key=${taskInput.value}>Edycja</button>
    </div><button type="button" data-delete>X</button>`;