window.onload=function(){ $(window).bind("scroll",scrollFun); } var state=false; function scrollFun(){ var Height = $(".video").offset().top; var scrollTop = $(window).scrollTop(); if(scrollTop>=Height){ state=true; if(state==true){ $(".face_png,.texi_png").hide(); $(".face_gif,.texi_gif").show(); imgShow($(".face_gif")); $(window).unbind("scroll",scrollFun); // $(window).bind("scroll",scrollFun2); //当有两个滚动判断时,在此绑定下一个 } } }