JS实现多物体运动的方法详解(2)

<script>
    window.onload = function(){
      var liTags = document.getElementsByTagName('li');
      for(var i=0;i<liTags.length;i++){
         liTags[i].timer = null;// 给每个li都添加一个timer
         liTags[i].onmouseover = function () {
         startMove(this,400);
         }
         liTags[i].onmouseout = function () {
         startMove(this,200);
         }
      }
    }
    function startMove(obj,iTarget) {
      clearInterval(obj.timer);
      obj.timer = setInterval(function () {
        var iSpeed = (iTarget - obj.offsetWidth)/10;
        iSpeed = iSpeed>0 ?Math.ceil(iSpeed):Math.floor(iSpeed);
        if(obj.offsetWidth == iTarget){
          clearInterval(obj.timer);
        }else{
          obj.style.width = obj.offsetWidth+iSpeed+'px';
        }
      },30);
    }
</script>

<script>
  window.onload = function () {
    var aImgs = document.getElementsByTagName('img');
    for(var i=0;i<aImgs.length;i++){
      aImgs[i].timer = null;
      aImgs[i].alpha = 100; // 把公用的alpha改成每个img对象都有的属性
      aImgs[i].onmouseover = function () {
        startMove(this,30);
      }
      aImgs[i].onmouseout = function () {
        startMove(this,100);
      }
    }
  }
  // var alpha = 100; 这里alpha在多物体运动里 不能公用
  function startMove(obj,iTarget) {
    clearInterval(obj.timer);
    var iSpeed = (iTarget - obj.alpha)/10;
      iSpeed = iSpeed>0 ? Math.ceil(iSpeed): Math.floor(iSpeed);
    obj.timer = setInterval(function(){
      if(obj.alpha == iTarget){
        clearInterval(obj.timer);
      }else{
        obj.alpha += iSpeed;
        obj.style.opacity =obj.alpha/100;
        obj.style.filter = 'alpha(opacity:'+obj.alpha+')';
      }
    },30);
  }
</script>