js渐隐渐入渐出效果 fadeOut fadeIn

    //fadeOut
    //function start
    function fadeOut(ele,speed){
        var ele=document.getElementById(ele);
        var opacitynum=ele.style.opacity||1;
        var speed=(speed/100)||10;
        function opacityOff(){
            if(opacitynum>0){
                ele.style.opacity=opacitynum=(opacitynum-0.01).toFixed(2);
            }else{
                clearInterval(opacityt);
            }
        }
        var opacityt=setInterval(opacityOff,speed);
    }
    //function end

    //fadeIn
    //function start
    function fadeIn(ele,speed){
        var ele=document.getElementById(ele);
        var opacitynum=ele.style.opacity||0;
        var speed=(speed/100)||10;
        function opacityAdd(){
            if(opacitynum<1){
                ele.style.opacity=opacitynum=(parseFloat(opacitynum)+0.01).toFixed(2);
            }else{
                clearInterval(opacityt);
            }
        }
        var opacityt=setInterval(opacityAdd,speed);
    }
    //function end