'Back to top' on scroll top at footer

问题

Using some examples I've seen around I've got a back to the top button to appear and work when you scroll down a page, however is there a way of making the button stick to the bottom of the screen until you reach the footer where it will stick to the top of the footer?

this is my code so far:

<script type="text/javascript" defer="defer">
    $(window).scroll(function() {
        if ($(this).scrollTop()) {
            $("#toTop").fadeIn();
        } else {
            $("#toTop").fadeOut();
        }
    });


    $("#toTop").click(function() {
        $("html, body").animate({scrollTop: 0}, 1000);
    });
</script>

<style type="text/css">
    .backtotop_button_wrap {width:100%; background:white; height:auto;}
    .backtotop_button_height {width:100%; height:55px;}
    #toTop {display:none; position: fixed; right:0; bottom:0; width:100px; height:auto; background:white; float:right; padding:10px; text-align:center; border:1px solid black; line-height:12px;}
    #footer {width:100%; height:500px; color:white; text-align:center; background:#313131; border-top:1px solid black;}
</style>

<div class="backtotop_button_wrap">
    <div class="backtotop_button_height">
        <div id="toTop">^<br />Back to the Top</div>
    </div>
</div>
<div id="footer">
Footer
</div>

I've also made a Jfiddle here: http://jsfiddle.net/0Lge6wqq/

回答1:

Change the html position of #toTop into the #footer. When the window reaches the height of the footer. #toTop changes from being fixed to being relative.

     if($(window).scrollTop() + $(window).height() < $(document).height() - $("#footer").height()){
            $('#toTop').css("position","fixed");    //resetting it
            $('#toTop').css("bottom","0"); //resetting it
}
else {
            $('#toTop').css("position","relative"); // make it related
            $('#toTop').css("bottom","60px"); // 60 px, height of #toTop
 }

jsfiddle

http://jsfiddle.net/0Lge6wqq/4/

来源：https://stackoverflow.com/questions/27780145/back-to-top-on-scroll-top-at-footer

标签

jquery

html

css

footer