html文档没有足够的高度时，菜单固定在滚动条顶部的问题？

Question

I do a menu fixed top when scroll, it ok with some pages have large height, but in page has not enough height, this script loop:

Example:

I have menu with height 50px and i write a script:

if ($(this).scrollTop() > 50){
    // add class fixed
} else { //remove class }

• on pages with large height this run: scroll(over 50px) > add class
• on pages with small height this run: scroll(over 50px) > add class > remove class

Please see this example: http://jsfiddle.net/F4BmP/2930/

Answer 1

Use this javascript:

$(document).ready(function(){
var elementPosition = $('.menu').offset();

$(window).scroll(function(){
        if($(window).scrollTop() > elementPosition.top){
              $('.menu').css('position','fixed').css('top','0');
              $('.menu').css('width','100%');
              $('.menu').css('z-index','500');
        } else {
            $('.menu').css('position','static');
        }    
});
});

Well, this code is working on my menubar, even if screen size is different .

Answer 2

Basic concept is user has to see the menu while scrolling the page.

But in your functionality is correct.There is no much content and User can see the menu in current screen itself. If there is more content user can scroll and get sticky menu always on top.

If you really want to make browser scroll you can give min-height for container.

Example

.containerclassname{
  min-height: 1500px;
}

Answer 3

I tested your code in firefox and also in chrome , the issue seems to be in chrome . i reworked the code both html and JS and it works fine in chrome, for for that matter in any browser .

heres what should probably work for you :

 $(document).ready(function(){
             $(window).scroll(function (e) {
                    $el = $('.nav');
                    if ($(this).scrollTop() > 100) {
                        $('.nav').addClass("fixedNav");
                    }else {
                        $('.nav').removeClass("fixedNav");
                    }
                });
             });

the entire code is enclosed in a fiddle .

Link to fiddle

Kind regards .

Alexander .

Answer 4

Finally, i find a solution for my problem.

Reason make problem is HTML document lost height when menu change from static to fixed.Examble: Browser has 500px and has a scrollbar, when user scroll my menu change to fixed and browser lost 50px of menu, so browser not enough height to has scrollbar, it will return to top page and do code lines in ELSE statement.

So i add a div wrap my menu and set height the same height with my menu, this will make the height of document always the same on before and after scroll:

<div id="wrap" style="height:50px;width:100%">
      <div id="mymenu"></div>
</div>

This solution solve my problem.