JavaScript手风琴效果不行,跟伪类有关吗?

unknown pseudo-class or pseudo-element "visible" 每次我试着用它。有什么问题吗?

$("div.example").hide();
$("input.exampleButton").click(function(){
    $("div.example:visible").slideUp("slow");
    $(this).parent().next().slideDown("slow");
    //return false; if you don't want the link to follow
});

这是HTML

input type="button" value="See An Example" class="exampleButton" />
<div class="example">
    ...content
</div>
input type="button" value="See An Example" class="exampleButton" />
<div class="example">
    ...content
</div>