JavaScript CSS 动画只工作一次

Question

我有一个银行应用程序，它有一只 super 酷的手放下一枚硬币到存钱 jar 中。问题是，这只手只掉了一次硬币，然后就停止工作了。

这是我的代码:

* {
  margin:0px;
  padding:0px;
}

body {
  background-image:url('../images/bg.png');
}

@keyframes moveDown {
  0% {}
  100% {margin-top:-220px;}
}

@keyframes fadeIn {
  0% {opacity:0;}
  90%{opacity:1}
  100%{opacity:0;}
}

#hand {
  height:300px;
  width:300px;
  position:absolute;
  left:50%;
  margin-left:-120px;
  margin-top:-350px;
  background-image:url("../images/hand.png");
  opacity:0;
}

#pigBox {
  margin-left:auto;
  margin-right:auto;
  height:600px;
  width:500px;
  margin-top:250px;
  position:relative;

  img {
    margin:0px 50px;
  }

}

input[type=text] {
  float:left;
  display:block;
  font-size:2em;
  width:500px;
  border-radius:10px;
  border:solid 2px pink;
  margin-top:10px;
  font-family: 'Gochi Hand', cursive;
  text-align:center;
  padding:2px;
}

#deposit {
  float:left;
  display:block;
  font-family: 'Gochi Hand', cursive;
  font-size:2em;
  clear:left;
  width:200px;
  margin:10px 25px;
  border-radius:10px;
  background-color:pink;
  border:solid 2px pink;
  padding:2px;
  cursor:pointer;

  &:hover {
    background-color:white;
  }
}

#withdraw {
  float:left;
  display:block;
  font-family: 'Gochi Hand', cursive;
  font-size:2em;
  width:200px;
  margin:10px 25px;
  border-radius:10px;
  background-color:pink;
  border:solid 2px pink;
  padding:2px;
  cursor:pointer;

  &:hover {
    background-color:white;
  }
}

label {
  text-align:center;
  display:block;
  font-family: 'Gochi Hand', cursive;
  font-size:2.5em;
  border-radius:10px;
  width:300px;
  margin-left:100px;
  margin-right:100px;
  margin-top:5px;
  margin-bottom:-15px;
}

document.getElementById('balance').value = "1000"

var balance = document.getElementById('balance').value;
var deposit = document.getElementById('deposit');
var withdraw = document.getElementById('withdraw');
var hand = document.getElementById('hand');

deposit.addEventListener('click', depositCash);
withdraw.addEventListener('click', withdrawCash);

function depositCash() {
  var depositAmt = prompt('How much would you like to deposit?');

  if(depositAmt != Number(depositAmt)) {
    return alert('Please enter a valid integer.');
  }
  else if (Number(depositAmt) < 0) {
    return alert('Please enter a positive integer.');
  }

  hand.style.animation = 'moveDown 1.5s ease-in-out, fadeIn 1.5s ease-in-out';
  balance = Number(balance) + Number(depositAmt);
  document.getElementById('balance').value = balance;
}

function withdrawCash() {
  var withdrawAmt = prompt('How much you you like to withdraw?');

  if(withdrawAmt != Number(withdrawAmt)) {
    return alert('Please enter a valid integer.');
  }
  else if (Number(withdrawAmt) < 0) {
    return alert('Please enter a positive integer.');
  }
  else if(withdrawAmt > balance) {
    return alert("Your balance isn't large enough to withdraw that amount!")
  }


  balance = Number(balance) - Number(withdrawAmt);
  document.getElementById('balance').value = balance;
}

<section id="pigBox">
      <div id="hand"></div><!-- end of hand-->
      <img src="images/pig.png" />
      <label>Balance: </label><input type="text" id="balance" />
      <button id="deposit"> Deposit </button>
      <button id="withdraw"> Withdraw </button>
  </section><!-- end of pigBox-->

<a href="http://imgur.com/FxwmGFi"><img src="http://i.imgur.com/FxwmGFi.png" title="source: imgur.com" /></a>

请注意将钱存入存钱 jar 时的手型动画。

大家有什么想法吗？

谢谢!

Answer 1

是因为CSS animations don't automatically restart .特别是因为您没有定义时间循环，所以它只执行一次。

一种方法是使用 .addClass('x').removeClass('x') 来重新触发定义在类 X 上的动画。

.addClass() 当然是 jQuery。您可以在 vanilla JS 中执行相同的操作，例如，使用 hand.className += 'my-animation';并按照以下方法在方法顶部重置。

//ref: https://css-tricks.com/restart-css-animation/

document.getElementById('balance').value = "1000"

var balance = document.getElementById('balance').value;
var deposit = document.getElementById('deposit');
var withdraw = document.getElementById('withdraw');
var hand = document.getElementById('hand');

deposit.addEventListener('click', depositCash);
withdraw.addEventListener('click', withdrawCash);

function depositCash() {
  hand.className = 'randoImage';
  var depositAmt = prompt('How much would you like to deposit?');

  if(depositAmt != Number(depositAmt)) {
    return alert('Please enter a valid integer.');
  }
  else if (Number(depositAmt) < 0) {
    return alert('Please enter a positive integer.');
  }

  hand.className += ' my-animation';
  balance = Number(balance) + Number(depositAmt);
  document.getElementById('balance').value = balance;
}

function withdrawCash() {
  var withdrawAmt = prompt('How much you you like to withdraw?');

  if(withdrawAmt != Number(withdrawAmt)) {
    return alert('Please enter a valid integer.');
  }
  else if (Number(withdrawAmt) < 0) {
    return alert('Please enter a positive integer.');
  }
  else if(withdrawAmt > balance) {
    return alert("Your balance isn't large enough to withdraw that amount!")
  }


  balance = Number(balance) - Number(withdrawAmt);
  document.getElementById('balance').value = balance;
}

.randoImage {
  width: 25px;
  height: 25px;
  background-image: url(data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVSKudfOulrSOp3WOyDZu6QdvCchPGolfO0o/XBs/fNwfjZ0frl3/zy7////wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAkAABAALAAAAAAQABAAAAVVICSOZGlCQAosJ6mu7fiyZeKqNKToQGDsM8hBADgUXoGAiqhSvp5QAnQKGIgUhwFUYLCVDFCrKUE1lBavAViFIDlTImbKC5Gm2hB0SlBCBMQiB0UjIQA7);
}

* {
  margin:0px;
  padding:0px;
}

@keyframes moveDown {
  0% {}
  100% {margin-top:-220px;}
}

@keyframes fadeIn {
  0% {opacity:0;}
  90%{opacity:1}
  100%{opacity:0;}
}

#hand {
  height:300px;
  width:300px;
  position:absolute;
  left:50%;
  margin-left:-120px;
  margin-top:-350px;
  /*background-image:url("../images/hand.png");*/
  opacity:0;
}

#pigBox {
  margin-left:auto;
  margin-right:auto;
  height:600px;
  width:500px;
  margin-top:250px;
  position:relative;

  img {
    margin:0px 50px;
  }

}

input[type=text] {
  float:left;
  display:block;
  font-size:2em;
  width:500px;
  border-radius:10px;
  border:solid 2px pink;
  margin-top:10px;
  font-family: 'Gochi Hand', cursive;
  text-align:center;
  padding:2px;
}

#deposit {
  float:left;
  display:block;
  font-family: 'Gochi Hand', cursive;
  font-size:2em;
  clear:left;
  width:200px;
  margin:10px 25px;
  border-radius:10px;
  background-color:pink;
  border:solid 2px pink;
  padding:2px;
  cursor:pointer;

  &:hover {
    background-color:white;
  }
}

#withdraw {
  float:left;
  display:block;
  font-family: 'Gochi Hand', cursive;
  font-size:2em;
  width:200px;
  margin:10px 25px;
  border-radius:10px;
  background-color:pink;
  border:solid 2px pink;
  padding:2px;
  cursor:pointer;

  &:hover {
    background-color:white;
  }
}

label {
  text-align:center;
  display:block;
  font-family: 'Gochi Hand', cursive;
  font-size:2.5em;
  border-radius:10px;
  width:300px;
  margin-left:100px;
  margin-right:100px;
  margin-top:5px;
  margin-bottom:-15px;
}

.my-animation {
  animation: moveDown 1.5s ease-in-out, fadeIn 1.5s ease-in-out;
}

<section id="pigBox">
      <div class="randoImage" id="hand"></div><!-- end of hand-->
      <img class="randoImage" />
      <!--<img src="images/pig.png" />-->
      <label>Balance: </label><input type="text" id="balance" />
      <button id="deposit"> Deposit </button>
      <button id="withdraw"> Withdraw </button>
  </section><!-- end of pigBox-->