Assuming this:
This is working for me today with FF 57:
function () {
// JQuery, today, doesn't play well with adding SVG elements - tricks required
$(selector_to_node_in_svg_doc).parent().prepend($(this).clone().text("Your"));
$(selector_to_node_in_svg_doc).text("New").attr("x", "340").text("New")
.attr('stroke', 'blue').attr("style", "text-decoration: line-through");
}
Makes: