新建html复制黏贴运行即可
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html
head
title鼠标跟随效果/title
style type="text/css"
html {
overflow: hidden;
}
body {
position: absolute;
height: 100%;
width: 100%;
margin:0;
padding:0;
}
#screen {
background:#000;
position: absolute;
width: 100%;
height: 100%;
}
#screen span {
background: #fff;
font-size: 0;
overflow: hidden;
width: 2px;
height: 2px;
}
/style
script type="text/javascript"
var Follow = function () {
var $ = function (i) {return document.getElementById(i)},
addEvent = function (o, e, f) {o.addEventListener ? o.addEventListener(e, f, false) : o.attachEvent('on'+e, function(){f.call(o)})},
OBJ = [], sp, rs, N = 0, m;
var init = function (id, config) {
this.config = config || {};
this.obj = $(id);
sp = this.config.speed || 4;
rs = this.config.animR || 1;
m = {x: $(id).offsetWidth * .5, y: $(id).offsetHeight * .5};
this.setXY();
this.start();
}
init.prototype = {
setXY : function () {
var _this = this;
addEvent(this.obj, 'mousemove', function (e) {
e = e || window.event;
m.x = e.clientX;
m.y = e.clientY;
})
},
start : function () {
var k = 180 / Math.PI, OO, o, _this = this, fn = this.config.fn;
OBJ[N++] = OO = new CObj(null, 0, 0);
for(var i=0;i360;i+=20){
var O = OO;
for(var j=10; j35; j+=1){
var x = fn(i, j).x,
y = fn(i, j).y;
OBJ[N++] = o = new CObj(O , x, y);
O = o;
}
}
setInterval(function() {
for (var i = 0; i N; i++) OBJ[i].run();
}, 16);
}
}
var CObj = function (p, cx, cy) {
var obj = document.createElement("span");
this.css = obj.style;
this.css.position = "absolute";
this.css.left = "-1000px";
this.css.zIndex = 1000 - N;
document.getElementById("screen").appendChild(obj);
this.ddx = 0;
this.ddy = 0;
this.PX = 0;
this.PY = 0;
this.x = 0;
this.y = 0;
this.x0 = 0;
this.y0 = 0;
this.cx = cx;
this.cy = cy;
this.parent = p;
}
CObj.prototype.run = function () {
if (!this.parent) {
this.x0 = m.x;
this.y0 = m.y;
} else {
this.x0 = this.parent.x;
this.y0 = this.parent.y;
}
this.x = this.PX += (this.ddx += ((this.x0 - this.PX - this.ddx) + this.cx) / rs) / sp;
this.y = this.PY += (this.ddy += ((this.y0 - this.PY - this.ddy) + this.cy) / rs) / sp;
this.css.left = Math.round(this.x) + 'px';
this.css.top = Math.round(this.y) + 'px';
}
return init;
}();
/script/head
body
div id="screen"/div
script type="text/javascript"
new Follow('screen', {speed: 4,
animR : 2,
fn : function (i, j) {
return {
x : j/4*Math.cos(i),
y : j/4*Math.sin(i)
}
}})
/script/body
/html
eval是为了 创建一个 span+i+.style :例如:
span1.style
span2.style
span3.style
span4.style
span5.style
……
第i个span对象的style的属性的引用然后赋值给thisspan 。只能这样写，因为i是变量。
至于那个括号，加不加都一样，我没看出什么意义来。
你问的问题就像：
这段代码里：i=message.length-1;
为什么不写成imessage.length呢？i和message.length都是正整数或0。
这是一个拖动元素的效果
div id="div" style="width:100px;height:100px;background-color:red;position: absolute;cursor: move"
/div
script
window.onload=function(){
var div=document.getElementById("div");
div.onmousedown=function(e){ //把onmousedown改成onclick就是你要的效果
var x= e.clientX-div.offsetLeft;
var y= e.clientY-div.offsetTop;
document.onmousemove=function(e){
div.style.left= e.clientX-x+"px";
div.style.top= e.clientY-y+"px";
}
document.onmouseup=function(){
document.onmousemove=null;
}
}
}
/script
