Js很简单的小星星跟随鼠标特效代码_Js鼠标跟随效果

Js封装方法
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+=20){
    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;
  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;
}();
调用很简单
new Follow('screen', {
 speed: 4,
 animR : 2,
 fn : function (i, j) {
  return {
   x : j/4*Math.cos(i),
   y : j/4*Math.sin(i)
  }
 }
})