代码就是这么写的！

<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;i<360;i+=10){
var O = OO;
for(var j=10; j<35; 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;
$("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>