function changeHight(){
var beforeHeight = $(".interaction").scrollTop();
$(".interaction").scrollTop($(".interaction").scrollTop()+20);
var afterHeight = $(".interaction").scrollTop();
if(beforeHeight == afterHeight){
//alert("ok");
}else{
setTimeout("changeHight()",5);
}
}
setTimeout("changeHight()",5);
关键示例代码:$("#id").scrollTop(500);