Back on top (with jQuery)

back-on-top.js

! function() {
    $(window).scroll(function() {
        $(this).scrollTop() > 300 ? $("#back-top").fadeIn() : $("#back-top").fadeOut()
    });
    var t = $("<div>");
    t.css({
        position: "relative",
        "text-align": "center"
    }), t.attr("id", "back-top");
    var a = $("<a>");
    t.attr("href", "javascript:;"), t.css({
        cursor: "pointer",
        position: "fixed",
        right: "75px",
        "z-index": "1000",
        width: "20px",
        height: "20px",
        "line-height": "20px",
        bottom: "90px"
    }), t.append(a);
    var i = $("<img>");
    i.attr("src", "https://raw.githubusercontent.com/glats/AngularJS101/master/chevron-up.png"), i.attr("heigth", "24"), i.attr("width", "24"), a.on("click", function() {
        $("body, html").animate({
            scrollTop: 0
        }, 800)
    }), a.append(i), $("body").append(t)
}();