如何在长时间执行JavaScript期间显示微调器？

Question

我已经玩了很长时间了，当我按下一个按钮然后在JavaScript函数执行后隐藏时，无法在CSS中显示一个微调器。这是我尝试用纯JavaScript做的事情的片段。

<button id="spinBtn" onclick="spinIt()">Spin it</button>
<div class="spinner" style="visibility:hidden;">

<script>
function spinIt() {
    document.getElementsByClassName("spinner").style.visibility = "visible";
    setTimeout(function () {
        // long code here
        document.getElementsByClassName("spinner").style.visibility = "hidden";
    }, 1); // give it a moment to redraw
}
</script>

http://jsfiddle.net/imparante/h9kLL1se/

Answer 1

尝试

使用document.getElementsByClassName而不是document.querySelectorAll，而是增加setTimeout时间间隔。

并且document.getElementsByClassName返回match元素的数组。要选择第一个元素，请使用document.getElementsByClassName('spinner')[0]

function spinIt() {
  document.querySelectorAll(".spinner")[0].style.visibility = "visible";
  setTimeout(function() {
    // long code here
    document.querySelectorAll(".spinner")[0].style.visibility = "hidden";
  }, 1000); // give it a moment to redraw
}

.spinner {
  margin: 100px auto;
  width: 20px;
  height: 20px;
  position: relative;
}
.container1 > div,
.container2 > div,
.container3 > div {
  width: 6px;
  height: 6px;
  background-color: #333;
  border-radius: 100%;
  position: absolute;
  -webkit-animation: bouncedelay 1.2s infinite ease-in-out;
  animation: bouncedelay 1.2s infinite ease-in-out;
  /* Prevent first frame from flickering when animation starts */
  -webkit-animation-fill-mode: both;
  animation-fill-mode: both;
}
.spinner .spinner-container {
  position: absolute;
  width: 100%;
  height: 100%;
}
.container2 {
  -webkit-transform: rotateZ(45deg);
  transform: rotateZ(45deg);
}
.container3 {
  -webkit-transform: rotateZ(90deg);
  transform: rotateZ(90deg);
}
.circle1 {
  top: 0;
  left: 0;
}
.circle2 {
  top: 0;
  right: 0;
}
.circle3 {
  right: 0;
  bottom: 0;
}
.circle4 {
  left: 0;
  bottom: 0;
}
.container2 .circle1 {
  -webkit-animation-delay: -1.1s;
  animation-delay: -1.1s;
}
.container3 .circle1 {
  -webkit-animation-delay: -1.0s;
  animation-delay: -1.0s;
}
.container1 .circle2 {
  -webkit-animation-delay: -0.9s;
  animation-delay: -0.9s;
}
.container2 .circle2 {
  -webkit-animation-delay: -0.8s;
  animation-delay: -0.8s;
}
.container3 .circle2 {
  -webkit-animation-delay: -0.7s;
  animation-delay: -0.7s;
}
.container1 .circle3 {
  -webkit-animation-delay: -0.6s;
  animation-delay: -0.6s;
}
.container2 .circle3 {
  -webkit-animation-delay: -0.5s;
  animation-delay: -0.5s;
}
.container3 .circle3 {
  -webkit-animation-delay: -0.4s;
  animation-delay: -0.4s;
}
.container1 .circle4 {
  -webkit-animation-delay: -0.3s;
  animation-delay: -0.3s;
}
.container2 .circle4 {
  -webkit-animation-delay: -0.2s;
  animation-delay: -0.2s;
}
.container3 .circle4 {
  -webkit-animation-delay: -0.1s;
  animation-delay: -0.1s;
}
@-webkit-keyframes bouncedelay {
  0%, 80%, 100% {
    -webkit-transform: scale(0.0)
  }
  40% {
    -webkit-transform: scale(1.0)
  }
}
@keyframes bouncedelay {
  0%, 80%, 100% {
    transform: scale(0.0);
    -webkit-transform: scale(0.0);
  }
  40% {
    transform: scale(1.0);
    -webkit-transform: scale(1.0);
  }
}

<p>
  <button id="comboBtn" onclick="spinIt()">Combo it</button>
</p>

<div class="spinner" style="visibility:hidden">
  <div class="spinner-container container1">
    <div class="circle1"></div>
    <div class="circle2"></div>
    <div class="circle3"></div>
    <div class="circle4"></div>
  </div>
  <div class="spinner-container container2">
    <div class="circle1"></div>
    <div class="circle2"></div>
    <div class="circle3"></div>
    <div class="circle4"></div>
  </div>
  <div class="spinner-container container3">
    <div class="circle1"></div>
    <div class="circle2"></div>
    <div class="circle3"></div>
    <div class="circle4"></div>
  </div>
</div>

Answer 2

document.getElementsByClassName返回许多元素（复数）。至少你必须这样做：

document.getElementsByClassName("spinner")[0].style.visibility = "visible";
                                          ^^^

虽然您应该遍历此元素列表并使所有微调器可见，或者您应该为您的微调器使用唯一的id并通过{{1}获取此特定微调器（单数）。