Task Manager

function solve() {
    function makeEl(type, text, clazz) {
        let el = document.createElement(type);
        if (text !== null) {
            el.textContent = text;
        }
        if (clazz !== null) {
            el.setAttribute('class', clazz);
        }
        return el;
    }

    function addToSection(section, art) {
        sectionMap[section].children[1].appendChild(art);
        return art;
    }

    function deleteArticle(e) {
        let art = e.target.parentNode.parentNode;
        art.remove();
        return art;
    }

    function removeButtons(art) {
        let btnDiv = art.children[3]
        art.removeChild(btnDiv);
        return art;
    }

    let btn = this.document.getElementById('add');
    let sections = document.getElementsByTagName('section');
    let sectionMap = {
        open: sections[1],
        inProgress: sections[2],
        complete: sections[3]
    };

    btn.addEventListener('click', function (e) {
        e.preventDefault();

        let title = document.getElementById('task').value;
        let description = document.getElementById('description').value;
        let date = document.getElementById('date').value;
        let dateRegex = new RegExp('^\\d{4}\\.\\d{2}\\.\\d{2}$');

        if (title === '' || description === '' || !dateRegex.test(date)) {
            console.log("Error");
            return
        }

        let art = document.createElement('article');

        art.appendChild(makeEl('h3', title, null));
        art.appendChild(makeEl('p', `Description: ${description}`, null));
        art.appendChild(makeEl('p', `Due Date: ${date}`, null));
        let btnDiv = makeEl('div', null, 'flex');

        let startBtn = makeEl('button', 'Start', 'green');
        startBtn.addEventListener('click', function (e) {
            let art = removeButtons(deleteArticle(e));
            let btnDiv = makeEl('div', null, 'flex');

            let delBtn = makeEl('button', 'Delete', 'red');
            delBtn.addEventListener('click', function (e) {
                deleteArticle(e);
            });
            btnDiv.appendChild(delBtn);

            let finishBtn = makeEl('button', 'Finish', 'orange');
            finishBtn.addEventListener('click', function (e) {
                addToSection('complete', removeButtons(deleteArticle(e)))
            });
            btnDiv.appendChild(finishBtn);

            art.appendChild(btnDiv);
            addToSection('inProgress', art)
        });
        btnDiv.appendChild(startBtn);

        let delBtn = makeEl('button', 'Delete', 'red');
        delBtn.addEventListener('click', function (e) {
            deleteArticle(e);
        });
        btnDiv.appendChild(delBtn);

        art.appendChild(btnDiv);
        addToSection('open', art)
    });
}