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$(document).ready(function(){
     $(window).scroll(function () {
            if ($(this).scrollTop() > 50) {
                $('#back-to-top').fadeIn();
            } else {
                $('#back-to-top').fadeOut();
            }
        });
        // scroll body to 0px on click
        $('#back-to-top').click(function () {
            $('#back-to-top').tooltip('hide');
            $('body,html').animate({
                scrollTop: 0
            }, 800);
            return false;
        });
        
        $('#back-to-top').tooltip('show');

});

<a id="back-to-top" href="#" class="btn btn-primary btn-lg back-to-top" role="button" title="Click to return on the top page" data-toggle="tooltip" data-placement="left">
	<span class="glyphicon glyphicon-chevron-up"></span>
</a>

.back-to-top {
    cursor: pointer;
    position: fixed;
    bottom: 20px;
    right: 20px;
    display:none;
}