Taken from an old post of mine, here's an example of both things that you want done together in one fiddle.
JSFiddle
JQuery:
function moveScroll() {
var scroll = $('#table-container').offset().top;
var anchor_top = $("#maintable").offset().top;
var anchor_bottom = $("#bottom_anchor").offset().top;
if (scroll > anchor_top && scroll < anchor_bottom) {
clone_table = $("#clone");
if (clone_table.length === 0) {
clone_table = $("#maintable").clone();
clone_table.attr({
id: "clone"
}).css({
position: "fixed",
"pointer-events": "none",
left: $("#maintable").offset().left + 'px',
top: 130
}).width($("#maintable").width());
$("#table-container").append(clone_table);
$("#clone").width($("#maintable").width());
$("#clone thead").css({
visibility: "true"
});
$("#clone tbody").css({
visibility: "hidden"
});
var footEl = $("#clone tfoot");
if (footEl.length) {
footEl.css({
visibility: "hidden"
});
}
}
} else {
$("#clone").remove();
}
}
$('#table-container').scroll(moveScroll);