帮我看看这段代码什么意思？
本帖最后由 yang131261 于 2013-08-29 16:59:51 编辑

 <script type="text/javascript">
/* ==== slider nameSpace ==== */
var slider = function() {
/* ==== private methods ==== */
function getElementsByClass(object, tag, className) {
var o = object.getElementsByTagName(tag);
for ( var i = 0, n = o.length, ret = []; i < n; i++) {
if (o[i].className == className) ret.push(o[i]);
}
if (ret.length == 1) ret = ret[0];
return ret;
}
function setOpacity (obj,o) {
if (obj.filters) obj.filters.alpha.opacity = Math.round(o);
else obj.style.opacity = o / 100;
}


/* ==== Slider Constructor ==== */
function Slider(oCont, speed, iW, iH, oP) {
this.slides = [];
this.over   = false;
this.S      = this.S0 = speed;
this.iW     = iW;
this.iH     = iH;
this.oP     = oP;
this.oc     = document.getElementById(oCont);
this.frm    = getElementsByClass(this.oc, 'div', 'slide');
this.NF     = this.frm.length;
this.resize();
for (var i = 0; i < this.NF; i++) {
this.slides[i] = new Slide(this, i);
}
this.oc.parent = this;
this.view      = this.slides[0];
this.Z         = this.mx;
/* ==== on mouse out event ==== */
this.oc.onmouseout = function () {
this.parent.mouseout();
return false;
}
}
Slider.prototype = {
/* ==== animation loop ==== */
run : function () {
this.Z += this.over ? (this.mn - this.Z) * .5 : (this.mx - this.Z) * .5;
this.view.calc();
var i = this.NF;
while (i--) this.slides[i].move();
},
/* ==== resize  ==== */
resize : function () {
this.wh = this.oc.clientWidth;//750
this.ht = this.oc.clientHeight; 
 
this.wr = this.wh * this.iW;// 460
this.r  = this.ht / this.wr;//0.43
this.mx = this.wh / this.NF;// 每个开始时的宽度 75
this.mn = (this.wh * (1 - this.iW)) / (this.NF - 1);// 32
},
/* ==== rest  ==== */
mouseout : function () {
this.over      = false;
setOpacity(this.view.img, this.oP);
}
}
/* ==== Slide Constructor ==== */
Slide = function (parent, N) {
this.parent = parent;
this.N      = N;
this.x0     = this.x1 = N * parent.mx;
this.v      = 0;
this.loaded = false;
this.cpt    = 0;
this.start  = new Date();
this.obj    = parent.frm[N];
this.txt    = getElementsByClass(this.obj, 'div', 'text');
this.img    = getElementsByClass(this.obj, 'img', 'diapo');
this.bkg    = document.createElement('div');
this.bkg.className = 'backgroundText';
this.obj.insertBefore(this.bkg, this.txt);
if (N == 0) this.obj.style.borderLeft = 'none';
this.obj.style.left = Math.floor(this.x0) + 'px';
       
   
   
setOpacity(this.img, parent.oP);
/* ==== mouse events ==== */
this.obj.parent = this;
this.obj.onmouseover = function() {
this.parent.over();
return false;
}
}
Slide.prototype = {
/* ==== target positions ==== */
calc : function() {
var that = this.parent;
// left slides
for (var i = 0; i <= this.N; i++) {
that.slides[i].x1 = i * that.Z;
}
// right slides
for (var i = this.N + 1; i < that.NF; i++) {
that.slides[i].x1 = that.wh - (that.NF - i) * that.Z;
}
},
/* ==== HTML animation : move slides ==== */
move : function() {
var that = this.parent;
var s = (this.x1 - this.x0) / that.S;
/* ==== lateral slide ==== */ 
 
if (this.N && Math.abs(s) > .5) {
this.obj.style.left = Math.floor(this.x0 += s) + 'px';
}
/* ==== vertical text ==== */
var v = (this.N < that.NF - 1) ? that.slides[this.N + 1].x0 - this.x0 : that.wh - this.x0;
if (Math.abs(v - this.v) > .5) {
this.bkg.style.top = this.txt.style.top = Math.floor(2 + that.ht - (v - that.Z) * that.iH * that.r) + 'px';
this.v = v;
this.cpt++;
} else {
if (!this.pro) {
/* ==== adjust speed ==== */
this.pro = true;
var tps = new Date() - this.start;
if(this.cpt > 1) {
that.S = Math.max(2, (28 / (tps / this.cpt)) * that.S0);
}
}
}
if (!this.loaded) {
if (this.img.complete) {
this.img.style.visibility = 'visible';
this.loaded = true;
}
}
},
/* ==== light ==== */
over : function () {
this.parent.resize();
this.parent.over = true;
setOpacity(this.parent.view.img, this.parent.oP);
this.parent.view = this;
this.start = new Date();
this.cpt = 0;
this.pro = false;
this.calc();
setOpacity(this.img, 100);
}
}
/* ==== public method - script initialization ==== */
return {
init : function() {
// create instances of sliders here
// parameters : HTMLcontainer name, speed (2 fast - 20 slow), Horizontal ratio, vertical text ratio, opacity
this.s1 = new Slider("slider", 12, 1.84/3, 1/3.2, 100);
setInterval("slider.s1.run();", 16);
}
}
}();

</script>

<div id="slider">
            <div class="slide"> <img class="diapo" src="imgs/sf10.jpg" onload="resize(this,500,200)"  alt="帮小弟我看看这段代码什么意思"/>
              <div class="text"> <span class="title">1</span>石家庄植物园好时光欢乐城</div> 
 
            </div>
            <div class="slide"> <img class="diapo" src="imgs/sf14.jpg" onload="resize(this,500,200)"  alt="帮小弟我看看这段代码什么意思"/>
              <div class="text"> <span class="title">2</span>石家庄植物园好时光欢乐城</div>
            </div>
            <div class="slide"> <img class="diapo" src="imgs/sf24.jpg" onload="resize(this,500,200)"  alt="帮小弟我看看这段代码什么意思"/>
              <div class="text"> <span class="title">3</span>石家庄植物园好时光欢乐城</div>
            </div>
            <div class="slide"> <img class="diapo" src="imgs/sf04.jpg" onload="resize(this,500,200)"  alt="帮小弟我看看这段代码什么意思"/>
</div>

94行那段代码this.parent 这个对应传过来的值是slider 但是over这个函数不是在slide里么，js新手不太明白，求解释，

[解决办法]
注意行68，this.parent指向Slide的parent属性，这个属性在行68被指向了传进来的parent参数。
过程是：在行32，调用构造函数Slide时，将this也就是slider的实例作为parent参数传入Slide，跳到行68，此时Slide的parent属性被赋值为slider了。所以over里调用this.parent就指向了slider了。