“内容：”上的 css 动画在 Safari 和 Firefox 上不起作用

Question

我在:before 上设置了一个动画，它在 Chrome 上运行良好，但在 Safari（IOS9 iPhone 或 9 - El Capitan）上也不能在 Firefox 上运行。

.hey {
  color: white;
}
.hey:before {
  content: 'Hey \a there';
  white-space: pre;
  position: absolute;
  color: red;
 -moz-animation: heyThere 2250ms steps(11); /* for firefox */
  -webkit-animation: heyThere 2250ms steps(11); /* for safari, chrome & opera */
}

@keyframes heyThere {
    0% {content: "";}
    1% {content: "";}
    75% {content: "";}
    77% {content: "H";}
    80% {content: "He";}
    83% {content: "Hey";}
    85% {content: "Hey ";}
    87% {content: "Hey \a t";}
    90% {content: "Hey \a th";}
    93% {content: "Hey \a the";}
    95% {content: "Hey \a ther";}
    97% {content: "Hey \a there";}
    100% {content: "Hey \a there";}
}
@-moz-keyframes heyThere { /* animation for firefox */
    0% {content: "";}
    1% {content: "";}
    75% {content: "";}
    77% {content: "H";}
    80% {content: "He";}
    83% {content: "Hey";}
    85% {content: "Hey ";}
    87% {content: "Hey \a t";}
    90% {content: "Hey \a th";}
    93% {content: "Hey \a the";}
    95% {content: "Hey \a ther";}
    97% {content: "Hey \a there";}
    100% {content: "Hey \a there";}
}
@-webkit-keyframes heyThere { /* animation for chrome, safari & opera */
    0% {content: "";}
    1% {content: "";}
    75% {content: "";}
    77% {content: "H";}
    80% {content: "He";}
    83% {content: "Hey";}
    85% {content: "Hey ";}
    87% {content: "Hey \a t";}
    90% {content: "Hey \a th";}
    93% {content: "Hey \a the";}
    95% {content: "Hey \a ther";}
    97% {content: "Hey \a there";}
    100% {content: "Hey \a there";}
}

<div class="hey">Hey there</div>

Answer 1

@asimovwasright 答案是正确的。

为了避免在 css 上出现如此多的重复，我使用带有 SCSS 的 @for 循环遍历所有可用跨度（在本例中为 8）

.hey {
    span {
        color: transparent;
        animation: heyThere 500ms ease-out;
        animation-fill-mode: forwards;

        $chars: 8;
        @for $i from 1 through $chars {
            &:nth-of-type(#{$i}) {
                animation-delay: 1200+70ms*$i;
            }
        }
    }
}

还有 HTML：

<h2 class="hey">
   <span>H</span>
   <span>e</span>
   <span>y</span>
   <br>
   <span>t</span>
   <span>h</span>
   <span>e</span>
   <span>r</span>
   <span>e</span>
</h2>

Answer 2

正如@Pavan Kumar Jorrigala 所述，除了桌面版 Chrome 之外，无法为伪元素的 content 属性设置动画。

这是你想要达到的目标的一种向后的方法：

jsfiddle

.hey span {
  color: transparent;
  animation: heyThere 100ms;
  animation-fill-mode: forwards;
}

.hey span:nth-child(1) {
  animation-delay: 100ms;
}
.hey span:nth-child(2) {
  animation-delay: 300ms;
}
.hey span:nth-child(3) {
  animation-delay: 500ms;
}
.hey span:nth-child(4) {
  animation-delay: 700ms;
}
.hey span:nth-child(5) {
  animation-delay: 900ms;
}
.hey span:nth-child(6) {
  animation-delay: 1100ms;
}
.hey span:nth-child(7) {
  animation-delay: 1300ms;
}
.hey span:nth-child(8) {
  animation-delay: 1500ms;
}

@keyframes heyThere {
    0% {color: transparent;}
  100% {color: red;}
}

<div class="hey">
  <span>H</span>
  <span>e</span>
  <span>y&nbsp;</span>
  <span>T</span>
  <span>h</span>
  <span>e</span>
  <span>r</span>
  <span>e</span>
</div>

Answer 3

我也翻遍了整个web我没有发现任何东西，根据下面的参考我们只能用JavaScript来实现。

在我自己的测试中，动画内容只能在稳定的桌面上运行 Chrome（撰写本文时为 v46）。其他地方不支持。没有野生动物园 在桌面或 iOS 上。没有火狐。没有 IE。这些浏览器中的每一个都将 忽略动画，只显示伪中的原始内容 元素。

Reference

Answer 4

尝试在 :before 中添加显示属性。例如，添加 display:block;看看这是否会影响动画。

Answer 5

在 safari 和 firefox 中，代码不是动画，相反，您必须编写 -moz-animation 和 -webkit-animation，如下代码：

.hey {
  color: white;
}
.hey:before {
  content: 'Hey \a there';
  white-space: pre;
  position: absolute;
  color: red;
  animation: heyThere 2250ms steps(11);
  -moz-animation: heyThere 2250ms steps(11); /* for firefox */
  -webkit-animation: heyThere 2250ms steps(11); /* for safari, chrome & opera */
}

@keyframes heyThere {
    0% {content: "";}
    1% {content: "";}
    75% {content: "";}
    77% {content: "H";}
    80% {content: "He";}
    83% {content: "Hey";}
    85% {content: "Hey ";}
    87% {content: "Hey \a t";}
    90% {content: "Hey \a th";}
    93% {content: "Hey \a the";}
    95% {content: "Hey \a ther";}
    97% {content: "Hey \a there";}
    100% {content: "Hey \a there";}
}
@-moz-keyframes heyThere { /* animation for firefox */
    0% {content: "";}
    1% {content: "";}
    75% {content: "";}
    77% {content: "H";}
    80% {content: "He";}
    83% {content: "Hey";}
    85% {content: "Hey ";}
    87% {content: "Hey \a t";}
    90% {content: "Hey \a th";}
    93% {content: "Hey \a the";}
    95% {content: "Hey \a ther";}
    97% {content: "Hey \a there";}
    100% {content: "Hey \a there";}
}
@-webkit-keyframes heyThere { /* animation for chrome, safari & opera */
    0% {content: "";}
    1% {content: "";}
    75% {content: "";}
    77% {content: "H";}
    80% {content: "He";}
    83% {content: "Hey";}
    85% {content: "Hey ";}
    87% {content: "Hey \a t";}
    90% {content: "Hey \a th";}
    93% {content: "Hey \a the";}
    95% {content: "Hey \a ther";}
    97% {content: "Hey \a there";}
    100% {content: "Hey \a there";}
}

`