前端这一段用：

<div class="ui black huge launch right attached button" id="back_to_index" style="width: 70px;">
    <i class="icon list layout"></i>
    <span class="text" id="back_to_index_word" style="display: none;">返回首页</span>
</div>

然后依次引用了jQurey,jQurey.easing 在对应 controller 的 coffee 中写了：

$back = $("#back_to_index")
$backword = $("#back_to_index_word")
$(document).ready ->
    $back.mouseenter ->
        $back.animate( {'width':'175px'} , { duration:1000,easing:'jswing' })
        $backword.css("display","inline")
        return

    $back.mouseleave ->
        $back.animate( {'width':'70px'} , { duration:1000,easing:'easeInOutCirc' })
        $backword.css("display","none")
        return
    return

然后 mouseenter 和 mouseleave 死活就是不能激活……没高明白问题出在哪里了…………