在页面中，如果页面长度过大，滑动页面时，头部导航栏则会跟着划走。
我的头部导航栏代码为：
<div class="headbar">
<center class="headbarTitle">通讯录</center>
</div>
固定头部导航栏的方法：引入sticky.js，再加上
//头部导航固定
$(".headbar").sticky(
{
topSpacing: 0
})
即可。
sticky.js代码如下：
(function (factory) {
if (typeof define === 'function' && define.amd) {
// AMD. Register as an anonymous module.
define(['jquery'], factory);
} else if (typeof module === 'object' && module.exports) {
// Node/CommonJS
module.exports = factory(require('jquery'));
} else {
// Browser globals
factory(jQuery);
}
}(function ($) {
var slice = Array.prototype.slice; // save ref to original slice()
var splice = Array.prototype.splice; // save ref to original slice()
var defaults = {
topSpacing: 0,
bottomSpacing: 0,
className: 'is-sticky',
wrapperClassName: 'sticky-wrapper',
center: false,
getWidthFrom: '',
widthFromWrapper: true, // works only when .getWidthFrom is empty
responsiveWidth: false,
zIndex: '100'
},
$window = $(window),
$document = $(document),
sticked = [],
windowHeight = $window.height(),
scroller = function () {
var scrollTop = $window.scrollTop(),
documentHeight = $document.height(),
dwh = documentHeight - windowHeight,
extra = (scrollTop > dwh) ? dwh - scrollTop : 0;
for (var i = 0, l = sticked.length; i < l; i++) {
var s = sticked[i],
elementTop = s.stickyWrapper.offset().top,
etse = elementTop - s.topSpacing - extra;
//update height in case of dynamic content
s.stickyWrapper.css('height', s.stickyElement.outerHeight());
if (scrollTop <= etse) {
if (s.currentTop !== null) {
s.stickyElement
.css({
'width': '',
'position': '',
'top': '',
'z-index': ''
});
s.stickyElement.parent().removeClass(s.className);
s.stickyElement.trigger('sticky-end', [s]);
s.currentTop = null;
}
} else {
var newTop = documentHeight - s.stickyElement.outerHeight() -
s.topSpacing - s.bottomSpacing - scrollTop - extra;
if (newTop < 0) {
newTop = newTop + s.topSpacing;
} else {
newTop = s.topSpacing;
}
if (s.currentTop !== newTop) {
var newWidth;
if (s.getWidthFrom) {
padding = s.stickyElement.innerWidth() - s.stickyElement.width();
newWidth = $(s.getWidthFrom).width() - padding || null;
} else if (s.widthFromWrapper) {
newWidth = s.stickyWrapper.width();
}
if (newWidth == null) {
newWidth = s.stickyElement.width();
}
s.stickyElement
.css('width', newWidth)
.css('position', 'fixed')
.css('top', newTop)
.css('z-index', s.zIndex);
s.stickyElement.parent().addClass(s.className);
if (s.currentTop === null) {
s.stickyElement.trigger('sticky-start', [s]);
} else {
// sticky is started but it have to be repositioned
s.stickyElement.trigger('sticky-update', [s]);
}
if (s.currentTop === s.topSpacing && s.currentTop > newTop || s.currentTop === null && newTop < s.topSpacing) {
// just reached bottom || just started to stick but bottom is already reached
s.stickyElement.trigger('sticky-bottom-reached', [s]);
} else if (s.currentTop !== null && newTop === s.topSpacing && s.currentTop < newTop) {
// sticky is started && sticked at topSpacing && overflowing from top just finished
s.stickyElement.trigger('sticky-bottom-unreached', [s]);
}
s.currentTop = newTop;
}
// Check if sticky has reached end of container and stop sticking
var stickyWrapperContainer = s.stickyWrapper.parent();
var unstick = (s.stickyElement.offset().top + s.stickyElement.outerHeight() >= stickyWrapperContainer.offset().top +
stickyWrapperContainer.outerHeight()) && (s.stickyElement.offset().top <= s.topSpacing);
if (unstick) {
s.stickyElement
.css('position', 'absolute')
.css('top', '')
.css('bottom', 0)
.css('z-index', '');
} else {
s.stickyElement
.css('position', 'fixed')
.css('top', newTop)
.css('bottom', '')
.css('z-index', s.zIndex);
}
}
}
},
resizer = function () {
windowHeight = $window.height();
for (var i = 0, l = sticked.length; i < l; i++) {
var s = sticked[i];
var newWidth = null;
if (s.getWidthFrom) {
if (s.responsiveWidth) {
newWidth = $(s.getWidthFrom).width();
}
} else if (s.widthFromWrapper) {
newWidth = s.stickyWrapper.width();
}
if (newWidth != null) {
s.stickyElement.css('width', newWidth);
}
}
},
methods = {
init: function (options) {
return this.each(function () {
var o = $.extend({}, defaults, options);
var stickyElement = $(this);
var stickyId = stickyElement.attr('id');
var wrapperId = stickyId ? stickyId + '-' + defaults.wrapperClassName : defaults.wrapperClassName;
var wrapper = $('<div></div>')
.attr('id', wrapperId)
.addClass(o.wrapperClassName);
stickyElement.wrapAll(function () {
if ($(this).parent("#" + wrapperId).length == 0) {
return wrapper;
}
});
var stickyWrapper = stickyElement.parent();
if (o.center) {
stickyWrapper.css({ width: stickyElement.outerWidth(), marginLeft: "auto", marginRight: "auto" });
}
if (stickyElement.css("float") === "right") {
stickyElement.css({ "float": "none" }).parent().css({ "float": "right" });
}
o.stickyElement = stickyElement;
o.stickyWrapper = stickyWrapper;
o.currentTop = null;
sticked.push(o);
methods.setWrapperHeight(this);
methods.setupChangeListeners(this);
});
},
setWrapperHeight: function (stickyElement) {
var element = $(stickyElement);
var stickyWrapper = element.parent();
if (stickyWrapper) {
stickyWrapper.css('height', element.outerHeight());
}
},
setupChangeListeners: function (stickyElement) {
if (window.MutationObserver) {
var mutationObserver = new window.MutationObserver(function (mutations) {
if (mutations[0].addedNodes.length || mutations[0].removedNodes.length) {
methods.setWrapperHeight(stickyElement);
}
});
mutationObserver.observe(stickyElement, { subtree: true, childList: true });
} else {
if (window.addEventListener) {
stickyElement.addEventListener('DOMNodeInserted', function () {
methods.setWrapperHeight(stickyElement);
}, false);
stickyElement.addEventListener('DOMNodeRemoved', function () {
methods.setWrapperHeight(stickyElement);
}, false);
} else if (window.attachEvent) {
stickyElement.attachEvent('onDOMNodeInserted', function () {
methods.setWrapperHeight(stickyElement);
});
stickyElement.attachEvent('onDOMNodeRemoved', function () {
methods.setWrapperHeight(stickyElement);
});
}
}
},
update: scroller,
unstick: function (options) {
return this.each(function () {
var that = this;
var unstickyElement = $(that);
var removeIdx = -1;
var i = sticked.length;
while (i-- > 0) {
if (sticked[i].stickyElement.get(0) === that) {
splice.call(sticked, i, 1);
removeIdx = i;
}
}
if (removeIdx !== -1) {
unstickyElement.unwrap();
unstickyElement
.css({
'width': '',
'position': '',
'top': '',
'float': '',
'z-index': ''
});
}
});
}
};
// should be more efficient than using $window.scroll(scroller) and $window.resize(resizer):
if (window.addEventListener) {
window.addEventListener('scroll', scroller, false);
window.addEventListener('resize', resizer, false);
} else if (window.attachEvent) {
window.attachEvent('onscroll', scroller);
window.attachEvent('onresize', resizer);
}
$.fn.sticky = function (method) {
if (methods[method]) {
return methods[method].apply(this, slice.call(arguments, 1));
} else if (typeof method === 'object' || !method) {
return methods.init.apply(this, arguments);
} else {
$.error('Method ' + method + ' does not exist on jQuery.sticky');
}
};
$.fn.unstick = function (method) {
if (methods[method]) {
return methods[method].apply(this, slice.call(arguments, 1));
} else if (typeof method === 'object' || !method) {
return methods.unstick.apply(this, arguments);
} else {
$.error('Method ' + method + ' does not exist on jQuery.sticky');
}
};
$(function () {
setTimeout(scroller, 0);
});
}));