jQuery Sticky Nav 和响应式设计的问题

Question

我遇到了一个问题，我无法用这段代码解决我在向下滚动页面时用来实现粘性导航的代码。

我希望 js 不做任何事情如果浏览器窗口宽度低于 720 像素，它可以工作，但仅在第一页加载时有效。我的意思是如果我在粘性导航处于活动状态时调整窗口大小，即使我将窗口大小调整到 720 像素以下，它仍然保持活动状态。这是 jQuery：

//Sticky Navi
jQuery(function($) {

// grab the initial top offset of the navigation 
var sticky_navigation_offset_top = $('.main-navigation').offset().top;
var browserWidth = $( window ).width();

// our function that decides weather the navigation bar should have "fixed" css position or not.
var sticky_navigation = function(){
    var scroll_top = $(window).scrollTop(); // our current vertical position from the top

    // if we've scrolled more than the navigation, change its position to fixed to stick to top,
    // otherwise change it back to relative
    if (scroll_top > sticky_navigation_offset_top && browserWidth > 720) { 
        $('.main-navigation').css({ 'position': 'fixed', 'top':0, 'z-index':999999, 'opacity': 0.9, 'box-shadow': '0px 3px 5px #393939' })
    } else {
        $('.main-navigation').css({ 'position': 'relative', 'opacity': 1, 'box-shadow': 'none' }); 
    }   
};

// run our function on load
sticky_navigation();

// and run it again every time you scroll
$(window).scroll(function() {
     sticky_navigation();
  });

});

感谢您的帮助

Answer 1

就像我在评论中所说，没有您的 HTML 和 CSS，我将无能为力，但这里有一些可行的方法。你有一个奇怪的功能需要修复。

function sticky_navigation() {

// grab the initial top offset of the navigation
var sticky_navigation_offset_top = $('.main-navigation').offset().top;
var browserWidth = $(window).width();
var scroll_top = $(window).scrollTop(); // our current vertical position from the top

// if we've scrolled more than the navigation, change its position to fixed to stick to top,
// otherwise change it back to relative
if ((scroll_top > $('.main-navigation').height()) && (browserWidth > 720)) {
    $('.main-navigation').css({ 'position': 'fixed', 'top':0, 'z-index':999999, 'opacity': 0.9, 'box-shadow': '0px 3px 5px #393939' });
} else {
    $('.main-navigation').css({ 'position': 'relative', 'opacity': 1, 'box-shadow': 'none' });
    }   
};

// and run it again every time you scroll
$(window).scroll(function() {
    sticky_navigation();
});

摆弄垃圾 HT​​ML：http://jsfiddle.net/cm4t6/