prismic-htmlSerializer.js

var htmlSerializer = function (element, content) {
    // Don't wrap images in a <p> tag
    if (element.type == "image") {
        return '<img src="' + element.url + '" alt="' + element.alt + '">';
    }

    // Add a class to hyperlinks
    if (element.type == "hyperlink") {
        return '<a class="some-link" href="' + element.url + '">' + content + '</a>';
    }

    // Return null to stick with the default behavior
    return null;
};
var html = doc.getStructuredText('blog-post.body').asHtml(getLinkResolver(), htmlSerializer);