JS Function to transform RSS feed into Bootstrap 4 Card

buildFeedCard.js

/*
* code to transform list of RSS feeds into bootstrap cards
* view my tutorial at https://knanne.github.io/posts/how-to-create-a-custom-rss-reader
* 1 DEPENDENCY - YQL: https://developer.yahoo.com/yql/
* Adhere to Google News GUIDELINES as standard for parsing RSS feeds
* (e.g. link to source, site author etc.)
* https://support.google.com/news/publisher/answer/4203?hl=en
*/

// make YQL query as url string
function make_query(url) {
    return 'https://query.yahooapis.com/v1/public/yql?q=' + encodeURIComponent('select * from feednormalizer where url="' + url + '"') + '&format=json';
};

// define date format
var date_options = { weekday: 'short', month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit'};

// define card creation functions
function make_cardheader(title, link, description) {
    return '\
    <div class="card-header text-left">\
        <h5 class="card-title"' + (description ? 'title="' + description + '"' : '' ) + '><a href="' + link + '" target="_blank">' + title + '</a></h5>\
    </div>';
};
function make_cardblock(link, title, date, source) {
    return '\
    <a href="' + link + '" target="_blank">\
        <div class="card-block text-center">\
            <div class="card-text text-muted">\
                <p><b>' + title + '</b><br>\
                    <small>' + date + '<br>\
                    ' + ( source ? ' - ' + source : '' ) + '\
                    </small>\
                </p>\
            </div>\
        </div>\
    </a>';
};
function make_cardfooter(last_updated) {
    return '\
    <div class="card-footer text-muted">\
        <small>Last Updated: ' + last_updated + '</small>\
    </div>';
};

// main build function
function buildFeedCard(url, container, feednum) {

    // call yahoo for json from rss feed, parse json
    $.getJSON(make_query(url), function (data, status, errorThrown) {
     if (status === 'success') {

        // define card string
        card_string = '';

        // open the feed card
        card_string = card_string + '<div id="feed_' + feednum + '" class="card d-inline-flex justify-content-center">';

        // get rss channel content from feed
        var content = (data.query.results.hasOwnProperty('rss') ? data.query.results.rss.channel : data.query.results.feed);
        var title = (content.title.constructor === Object ? content.title.content : content.title );
        var link = (content.link.constructor === Array ? content.link[0].href || content.link[0] : content.link.href || content.link);
        var description = (content.description ? content.description : null);

        // add header to card
        card_string = card_string + make_cardheader(title, link, description);

        // loop thru each content entry, get content
        $.each(content.item || content.entry, function(i, entry) {

            // get item content dynamically
            // because RSS feeds have different structures
            if (content.description == "Google News") {
                var title = entry.title.split(" - ")[0];
                var source = entry.title.split(" - ")[1];
            }
            else {
                var title = (entry.title.constructor === Object ? entry.title.content : entry.title );
                var source = (entry.hasOwnProperty('creator') ? entry.creator : (entry.hasOwnProperty('author') ? entry.author.name : null));
            }
            var link = (entry.link.constructor === Array ? entry.link[0].href || entry.link[0] : entry.link.href || entry.link);
            var date = new Date(Date.parse((entry.hasOwnProperty('pubDate') ? entry.pubDate : entry.updated)));
            date = date.toLocaleDateString('en-US', date_options);

            //append content to card
            card_string = card_string + make_cardblock(link, title, date, source);

            // dynamic trailing spacer
            if ( i < 2 ) { card_string = card_string + '<hr>'; } else { card_string = card_string + '<br>'; }

            // limit feed to 3 entries
            return i < 2;
        });

        // last updated as query created time
        var last_updated = new Date(Date.parse(data.query.created));
        last_updated = last_updated.toLocaleDateString('en-US', date_options);

        // append footer to card
        card_string = card_string + make_cardfooter(last_updated);

        // close the feed card
        card_string = card_string + '</div>';

        // append feed card to DOM
        $(container).append(card_string);

        } else if (status === 'error' || status === 'parsererror') {
            console.log(errorThrown);
        }
    });
}

A tutorial for using this gist can be found at https://knanne.github.io/posts/how-to-create-a-custom-rss-reader