index.js

addSendToXTV();
setInterval(addSendToXTV, 500);
addDelegateSendToXTVClickListeners();

function addSendToXTV() {
    var to_add =   `<div class="ProfileTweet-action ProfileTweet-action--reply send-to-xtv" style="float: right; margin-right: 10px; margin-top: 3px;">
                        <button class="ProfileTweet-actionButton js-actionButton send-to-xtv-button" type="button">
                            <div class="IconTextContainer">
                                <span class="ProfileTweet-actionCount">
                                    <span class="ProfileTweet-actionCountForPresentation send-to-xtv-text" aria-hidden="true">Send to XTV</span>
                                </span>
                            </div>
                        </button>
                    </div>`;
    
    $('.ProfileTweet-actionList.js-actions').each(function(index) {
        if ($(this).find('.send-to-xtv').length === 0) {
            $(this).append(to_add)
        }
    });
}

function addDelegateSendToXTVClickListeners() {
    document.querySelector('#page-container').addEventListener('click', function(e) {
        if (e.target.matches('.send-to-xtv-text')) {
            onClickSendToXTV($(e.target));
        }
    }, true);
}

function getTweetId(element) {
    return $(element).closest('.tweet').attr('data-tweet-id');
}

function getPageData() {
    return JSON.parse($('#init-data').val());
}

page_data = getPageData()

function onClickSendToXTV(button) {
    if($(button).text() == 'Done!') {
        alert("Tweet Already Submitted");
    } else {
        data_to_send = {
            'type': 'tweet',
            'tweet_id': getTweetId(button),
            'user' : {
                'fullName': page_data.fullName,
                'screenName': page_data.screenName,
                'userId': page_data.userId
            }
        }

        chrome.runtime.sendMessage(data_to_send, function(response) {
            console.log(data_to_send);
            console.log(response);
            if (response.success) {
                $(button).text('Done!');
            }
        });
    }  
}