匀速运动

function startMove(target){

          clearInterval( timer );

          timer = setInterval( function(){

              var speed = target - oDiv.offsetLeft>0 ? 7  : -7;

              if( Math.abs( target - oDiv.offsetLeft ) <  7 ){

                   oDiv.style.left = target + "px";

                   clearInterval( timer );

              }else{

                   oDiv.style.left = oDiv.offsetLeft +  speed + "px";

              }

          },30 )

     }

 

匀速透明运动

var alpha = 30;// 操作透明度的变化

function startMove(target){

          clearInterval( timer );

          timer = setInterval( function(){

              var speed = target-alpha>0 ? 1 : -1;

              if( target == alpha ){

                   clearInterval( timer );

              }else{

                   alpha += speed;

                   oDiv.style.opacity =  alpha/100;

              }

          },30 )

     }