Christmas Gifts Delivery [JavaScript DOM]

function solution() {
    let input = document.querySelector('input');
    let addGiftButton = getElementByInnerText('Add gift', 'button');

    let addedGifts = [];
    let sentGifts = [];
    let discardedGifts = [];

    let addedUL;
    let sentUL;
    let discardedUL;

    addGiftButton.addEventListener('click', (event) => {
        event.preventDefault();

        let giftName = input.value;
        addedGifts.push(giftName);
        addedGifts.sort();

        addedUL = getElementByInnerText('List of gifts', 'h2').parentNode.getElementsByTagName('ul')[0];

        addedUL.innerHTML = '';

        for (let i = 0; i < addedGifts.length; i++) {
            let liElement = `<li class="gift">${addedGifts[i]}<button id="sendButton">Send</button><button id="discardButton">Discard</button></li>`;

            addedUL.innerHTML += liElement;
        }

        input.value = '';

        let sendButton = document.querySelector('#sendButton');
        let discardButton = document.querySelector('#discardButton');

        sendButton.addEventListener('click', sendGift);
        discardButton.addEventListener('click', discardGift);
    });

    function getElementByInnerText(innerText, tagName) {
        let listOfElements = document.getElementsByTagName(tagName);

        for (let i = 0; i < listOfElements.length; i++) {
            if (listOfElements[i].innerText === innerText) {
                return listOfElements[i];
            }
        }
    }

    function sendGift(event) {
        let name = event.target.parentNode.firstChild.nodeValue;
        sentGifts.push(name);

        sentUL = getElementByInnerText('Sent gifts', 'h2').parentNode.getElementsByTagName('ul')[0];

        let list = buildUL(sentGifts, false);
        sentUL.innerHTML = list;

        buildListWithGifts(name);
    };

    function discardGift(event) {
        let name = event.target.parentNode.firstChild.nodeValue;
        discardedGifts.push(name);

        discardedUL = getElementByInnerText('Discarded gifts', 'h2').parentNode.getElementsByTagName('ul')[0];

        let list = buildUL(discardedGifts, false);
        discardedUL.innerHTML = list;

        buildListWithGifts(name);
    };

    function buildUL(elements, withButtons) {
        let list = "";

        for (let i = 0; i < elements.length; i++) {
            let buttons = "<button id='sendButton' onclick='sendGift(event)'>Send</button><button id='discardButton' onclick='discardGift(event)'>Discard</button>";
            let li = "<li class='gift'>" + elements[i];

            if (withButtons) {
                li += buttons;
            }

            li += "</li>";
            list += li;
        }

        return list;
    };

    function buildListWithGifts(elementToRemove) {
        if (elementToRemove) {
            const index = addedGifts.indexOf(elementToRemove);

            if (index > -1) {
                addedGifts.splice(index, 1);
            }
        }

        let list = buildUL(addedGifts, true);

        addedUL.innerHTML = list;
    }
}