js to achieve image fade-in and fade-out effect

Setz_index:function(){
        for(var i=0;i<this.Photo.length;i++){
            index=i;
            this.Photo[i].style.zIndex =this.Photo.length-i-1;
        }
    },

Animatezindex:function(math,count){
       for(var i=0;i<count;i++){
         for(var k=0;k<this.Photo.length;k++) {
            //console.log(1);
           var index = parseInt (this.Photo[k].style.zIndex ); //43210 04321 10432
           if(math=="n"){
             index++; //The dots change color from left to right if(index ==this.Photo.length){
                 index=0;
                 this.Photo[k].style.opacity =0;
                 this.Crclelist[k].style.background="#fff";
             }
             if(index==this.Photo.length-1){
                 this.Photo[k].style.opacity= 1;
                 this.Crclelist[k].style.background="pink";
                 this.Savecolor= this.Crclelist[k];

             }
           }
             else{
               index--; //The dot changes color from right to left if(index==-1){
                   index=this.Photo.length-1;
               }
               if(index==this.Photo.length-1){
                   this.Photo[k].style.opacity= 1;
                   this.Crclelist[k].style.background="pink";
                   this.Savecolor= this.Crclelist[k];
               }
               if(index==this.Photo.length-2){
                   this.Photo[k].style.opacity =0;
                   this.Crclelist[k].style.background="#fff";
               }
           }
             this.Photo[k].style.zIndex =index;
         }
       }
    },

Moren_set:function(){
        var that=this;
        that.Crclelist[0].style.background="pink";
        that.Savecolor =that.Crclelist[0];
        that.Bigblock.onmouseenter=function(){
            // console.log(1);
            window.cancelAnimationFrame(glider.Timeset);
        };
        that.Bigblock.onmouseleave=function(){
            glider.Timelines();
        }
        //Point events, follow the picture changes for(var i=0;i<that.Crclelist.length;i++){
            that.Crclelist[i].index=i;
            that.Crclelist[i].onmouseenter =function(){
              var oldindex=that.Savecolor.index;
              var newindex=this.index; //The index of the dot that the mouse slides into this refers to the sliding event of the current dot// console.log(newindex);
                if(newindex -oldindex >0) { //Enter from the right of the current dot var ri=newindex -oldindex;
                  // console.log(ri);
                    var le = that.Crclelist.length-ri;
                   // console.log(le);
                    if(ri<=le){
                        console.log("to the right",ri);
                        that.Animatezindex("n",ri);
                    }
                    if(ri>le){
                        console.log("to the left",le);
                        that.Animatezindex("s",le);
                    }
                }
                else if (newindex - oldindex < 0) {
                    var ri1=Math.abs(newindex-oldindex); //get the absolute value var le1=that.Crclelist.length-ri1;
                    if(ri1<=le1){
                        console.log("left", ri1);
                        that.Animatezindex("s",ri1);
                    }
                    if(ri1>le1){
                        console.log("right", le1);
                        that.Animatezindex("n",le1);
                    }

                }
            }
        }
    }

Timelines:function(){
        var nowtime = new Date().getTime();
        if((nowtime - glider.Oldtime) >= glider.TimeDely ){
            glider.Oldtime =nowtime;
            glider.Animatezindex ("n",1); //Change to the right}
        //You can use the setTimeout and setInterval methods to implement animation in the script.
        // But this may not be smooth enough and will take up extra resources.
        //The requestAnimationFrame method is used to notify the browser to resample the animation and play it in a loop.
        /*cancelAnimationFrame
        The cancelAnimationFrame method is used to cancel a previously scheduled animation frame update request. */
       glider.Timeset = window.requestAnimationFrame(glider.Timelines);
 }