data attr case
HTML
<div id="test" data-TFO='{"a": 123}'></div>
JavaScript
var n = "test";
var v = "lol";
$Root = $("#" + n);
console.log("1 data = %o", $Root.data("TFO"));
console.log("2 data = %o", $Root.data("tfo"));
$Root.data("tfo", $.extend({ k: v }, $Root.data("tfo")));
console.log("data = %o", $Root.data("tfo"));