CSS动画向前然后向后

Question

我正在尝试创建一个CSS动画，当用户单击汉堡菜单时，它会转换为x（步骤1），然后当用户再次单击它时，它会动画返回汉堡菜单（步骤2）。

步骤1有效，但我不知道如何反转动画。谢谢你的帮助！

http://jsfiddle.net/aX6Cf/

的HTML

<a id="mobile-menu">
    <span></span>
</a>

的CSS

@-webkit-keyframes rotate-plus {
  from {
    -webkit-transform:rotate(0deg);
  }
  to {
    -webkit-transform:rotate(45deg);
  }
}


@-webkit-keyframes rotate-minus {
  from {
    -webkit-transform:rotate(0deg);

  }
  to {
    -webkit-transform:rotate(-45deg);
  }
}

@-webkit-keyframes transition-1 {
  from {
    top: -6;
    transition: all .2s ease-out;

  }
  to {
    top: 0;
    transition: all .2s ease-out;
  }
}

@-webkit-keyframes transition-2 {
  from {
    bottom: -6;
    transition: all .2s ease-out;

  }
  to {
    bottom: 0;
    transition: all .2s ease-out;
  }
} 


body {
    margin: 20px;
}

#mobile-menu {
  display: block;
  position: relative;
  cursor: pointer; 
  width: 30px;
  padding: 6px 30px 9px 0; 
  box-sizing: border-box;
}

#mobile-menu span, 
#mobile-menu span:before, 
#mobile-menu span:after {
  height: 3px;
  width: 30px;
  background: #000;
  display: block;
  content: "";
  position: absolute;
  left: 50%;
  margin-left: -15px;
}

#mobile-menu span:before {
  top: -6px; 
}

#mobile-menu span:after {
  bottom: -6px;
}

#mobile-menu.active span {
  background-color: transparent;
}

#mobile-menu.active span:before {
-webkit-animation: rotate-plus .05s ease-out .1s forwards,
                   transition-1 .05s ease-out forwards;  
        animation: rotate-plus .05s ease-out .1s forwards,
                   transition-1 .05s ease-out forwards; 
}

#mobile-menu.active span:after {
-webkit-animation: rotate-minus .05s ease-out .1s forwards, 
                   transition-2 .05s ease-out forwards;
        animation: rotate-minus .05s ease-out .1s forwards, 
                   transition-2 .05s ease-out forwards;
}

jQuery的

$("#mobile-menu").click(function(){
    $("#mobile-menu").toggleClass("active");
});

Answer 1

我收回我在上面评论中所说的话。毕竟，看起来可以使用纯 CSS 来做到这一点......诀窍是正确使用转换延迟。

超文本标记语言

<a id="mobile-menu">
   <span></span>
</a>

CSS

body {
    margin: 20px;
}

#mobile-menu {
    display: block;
    position: relative;
    cursor: pointer; 
    width: 30px;
    padding: 6px 30px 9px 0; 
    box-sizing: border-box;
}

#mobile-menu span, 
#mobile-menu span:before, 
#mobile-menu span:after {
    height: 3px;
    width: 30px;
    background: #000;
    display: block;
    content: "";
    position: absolute;
    left: 50%;
    margin-left: -15px;
}

#mobile-menu span {
    transition: background-color .3s ease .3s;
    -webkit-transition: background-color .3s ease .3s;
}

#mobile-menu span:before {
    top: -6px;
    transition: top .2s ease .2s, transform .2s ease;
    -webkit-transition: top .2s ease .2s, -webkit-transform .2s ease;
}

#mobile-menu span:after {
    bottom: -6px;
    transition: bottom .2s ease .2s, transform .2s ease;
    -webkit-transition: bottom .2s ease .2s, -webkit-transform .2s ease;
}

#mobile-menu.active span {
    background-color: transparent;
    transition: background-color .3s ease;
    -webkit-transition: background-color .3s ease;
}

#mobile-menu.active span:before {
    top: 0;
    -webkit-transform: rotate(45deg);
    transform: rotate(45deg);
    transition: top .2s ease .1s, transform .2s ease .3s;
    -webkit-transition: top .2s ease .1s, -webkit-transform .2s ease .3s;
}

#mobile-menu.active span:after {
    bottom: 0;
    -webkit-transform: rotate(-45deg);
    transform: rotate(-45deg);
    transition: bottom .2s ease .1s, transform .2s ease .3s;
    -webkit-transition: bottom .2s ease .1s, -webkit-transform .2s ease .3s;
}

jQuery

$(function() {
    $("#mobile-menu").click(function(){
        $("#mobile-menu").toggleClass("active");
    });
})

在线演示