function DirectoryNav($h,config){
this.opts = $.extend(true,{
scrollThreshold:0.5, //滾動檢測閥值 0.5在瀏覽器窗口中間部位
scrollSpeed:700, //滾動到指定位置的動畫時間
scrollTopBorder:500, //滾動條距離頂部多少的時候顯示導航，如果為0，則壹直顯示
easing: 'swing', //不解釋
delayDetection:200, //延時檢測，避免滾動的時候檢測過於頻繁
scrollChange:function(){}
},config);
this.$win = $(window);
this.$h = $h;
this.$pageNavList = "";
this.$pageNavListLis ="";
this.$curTag = "";
this.$pageNavListLiH = "";
this.offArr = [];
this.curIndex = 0;
this.scrollIng = false;
this.init();
}
DirectoryNav.prototype = {
init:function(){
this.make();
this.setArr();
this.bindEvent();
},
make:function(){
//生成導航目錄結構,這是根據需求自己生成的。如果妳直接在頁面中輸出壹個結構那也挺好不用 搞js
$("body").append('<div class="directory-nav" id="directoryNav"><ul></ul><span class="cur-tag"></span><span class="c-top"></span><span class="c-bottom"></span><span class="line"></span></div>>');
var $hs = this.$h,
$directoryNav = $("#directoryNav"),
temp = [],
index1 = 0,
index2 = 0;
$hs.each(function(index){
var $this = $(this),
text = $this.text();
if(this.tagName.toLowerCase()=='h2'){
index1++;
if(index1%2==0) index2 = 0;
temp.push('<li class="l1"><span class="c-dot"></span>'+index1+'. <a class="l1-text">'+text+'</a></li>');
}else{
index2++;
temp.push('<li class="l2">'+index1+'.'+index2+' <a class="l2-text">'+text+'</a></li>');
}
});
$directoryNav.find("ul").html(temp.join(""));
//設置變量
this.$pageNavList = $directoryNav;
this.$pageNavListLis = this.$pageNavList.find("li");
this.$curTag = this.$pageNavList.find(".cur-tag");
this.$pageNavListLiH = this.$pageNavListLis.eq(0).height();
if(!this.opts.scrollTopBorder){
this.$pageNavList.show();
}
},
setArr:function(){
var This = this;
this.$h.each(function(){
var $this = $(this),
offT = Math.round($this.offset().top);
This.offArr.push(offT);
});
},
posTag:function(top){
this.$curTag.css({top:top+'px'});
},
ifPos:function(st){
var offArr = this.offArr;
//console.log(st);
var windowHeight = Math.round(this.$win.height() * this.opts.scrollThreshold);
for(var i=0;i<offArr.length;i++){
if((offArr[i] - windowHeight) < st) {
var $curLi = this.$pageNavListLis.eq(i),
tagTop = $curLi.position().top;
$curLi.addClass("cur").siblings("li").removeClass("cur");
this.curIndex = i;
this.posTag(tagTop+this.$pageNavListLiH*0.5);
//this.curIndex = this.$pageNavListLis.filter(".cur").index();
this.opts.scrollChange.call(this);
}
}
},
bindEvent:function(){
var This = this,
show = false,
timer = 0;
this.$win.on("scroll",function(){
var $this = $(this);
clearTimeout(timer);
timer = setTimeout(function(){
This.scrollIng = true;
if($this.scrollTop()>This.opts.scrollTopBorder){
if(!This.$pageNavListLiH) This.$pageNavListLiH = This.$pageNavListLis.eq(0).height();
if(!show){
This.$pageNavList.fadeIn();
show = true;
}
This.ifPos( $(this).scrollTop() );
}else{
if(show){
This.$pageNavList.fadeOut();
show = false;
}
}
},This.opts.delayDetection);
});
this.$pageNavList.on("click","li",function(){
var $this = $(this),
index = $this.index();
This.scrollTo(This.offArr[index]);
})
},
scrollTo: function(offset,callback) {
var This = this;
$('html,body').animate({
scrollTop: offset
}, this.opts.scrollSpeed, this.opts.easing, function(){
This.scrollIng = false;
//修正彈兩次回調 蛋疼
callback && this.tagName.toLowerCase()=='body' && callback();
});
}
};
//實例化
var directoryNav = new DirectoryNav($("h2,h3"),{
scrollTopBorder:0 ? //滾動條距離頂部多少的時候顯示導航，如果為0，則壹直顯示
});