jquery无缝图片轮播组件封装

<div id="box">  <ul id="banners">   <li class="banners-img"><img src="img/DSC_1913.JPG" /></li>   <li class="banners-img"><img src="img/DSC_1913.JPG" /></li>   <li class="banners-img"><img src="img/DSC_1913.JPG" /></li>   <li class="banners-img"><img src="img/DSC_1913.JPG" /></li>     </ul>  <ul class="num">   <li class="on"></li>  </ul>   <div class="btns btn_l"><</div>   <div class="btns btn_r">></div></div>

 #box{ width:100%; height:40.0em; overflow: hidden; position: absolute;} #box #banners{ width:500%; position: relative;} #box .banners-img{ float: left; width:20%; height:40.0em;} #box .banners-img img{ width:100%; height: 100%;} .num{ width:10%; height:2.0em; position: relative; top: 82%; left: 40%; -webkit-transform: rotate(-90deg); -ms-transform: rotate(-90deg); transform:rotate(-90deg);} .num li{ width:2.0em; height:100%; position: relative; border-radius: 50%; background-color: grey; } .num .on{ background-color: black;}  .btns{ width:1.0em; height:1.0em; background-color: rgba(0,0,0,0.5); position:relative; top:50%; color: white; font-size: 3.0em; text-align: center; line-height: 1.0em; cursor: pointer; display: none;} #box:hover .btns{ display: block;} .btn_l{ left: 0;} .btn_r{ right:0;}

function addImg(item,arrSrc){ //添加图片，这里需同时修改样式，读者可自行修改   for(let i = 0;i<item;i++){     item[i].attr('src',arrSrc[i]);            }          }        var srcs = ['img/DSC_1913.JPG','img/DSC_1914.JPG','img/DSC_1915.JPG','img/DSC_1916.JPG'];        addImg($('.banners-img img'),srcs);  var Clone = $("#banners li").first().clone(); //追加一张图片，轮到最后一张时能够自然过渡，这里初学者需慢慢体会 $("#banners").append(Clone); var Size = $("#banners li").size(); //alert(Size); for(var j=0;j<Size-2;j++){  $(".num").append("<li></li>");  }   //获取图片宽度 var imgWidth = parseInt($("#banners .banners-img").css("width")); //因宽度为百分比，窗口大小变化时需重新获取 window.onresize = function(){  var newWidth = $("#banners .banners-img").css("width");      imgWidth = parseInt(newWidth);  } //鼠标移到按钮时轮播 $(".num li").hover(function(){  var index = $(this).index();  i=index;  $("#box #banners").stop().animate({left:-i*imgWidth},500);  $("#box .num li").eq(i).addClass("on")  .siblings().removeClass("on");    })  //自动轮播  var t = setInterval(function(){   i++;   move();  },3000);  //鼠标移入时停止自动轮播  $("#box").hover(function(){   clearInterval(t);  },function(){   t = setInterval(function(){   i++;   move();  },3000);  })    //手动轮播  $("#box .btn_l").click(function(){   i--;   move();  });    $("#box .btn_r").click(function(){   i++;   move();  });   //封装一个运动函数  // alert(imgWidth);  function move(){   if(i==Size){ //当轮播到最后一张时过渡到第一张图片   $("#box #banners").css({left:0});   i=1;   }   if(i==-1){   $("#box #banners").css({left:-(Size-1)*imgWidth});   i=Size-2;   }   $("#box #banners").stop().animate({left:-i*imgWidth},500);   if(i==Size-1){   $("#box .num li").eq(0).addClass("on")   .siblings().removeClass("on");   }else{   $("#box .num li").eq(i).addClass("on")   .siblings().removeClass("on");   }     }