animationend事件未触发

Question

我正在尝试向元素添加animationend事件，但事件不会被触发。我做错了什么，我该如何解决？

JSFiddle

var btn = document.getElementById('btn');
var elem = document.getElementById('elem');
var timeOutFunc;

btn.addEventListener('click', function() {
  elem.classList.add('show');
  clearTimeout(timeOutFunc);
  timeOutFunc = setTimeout(function() {
    elem.classList.remove('show')
  }, 1000);
});


elem.addEventListener('animationend', function(e) {
  console.log('animation ended');
});

#elem {
  background-color: orange;
  width: 100px;
  height: 100px;
  opacity: 0;
  transition: opacity 500ms ease;
}
#elem.show {
  opacity: 1;
  transition: none;
}

<button id="btn">Press Me</button>
<div id="elem"></div>

Answer 1

有两个独立的动画事件。

1. animationend
2. transitionend

使用css transition时使用transitionend，使用@keyframes/animation时，请使用animationend。

Answer 2

您需要修改元素的动画样式属性，这是您在Jsfiddle

的更新示例

    #elem {
       background-color: orange;
       width: 100px;
       height: 100px;
       opacity: 0;
       transition: opacity 500ms ease;
       }
      /* Chrome, Safari, Opera */
     @-webkit-keyframes myopacity {
          0%   { opacity: 0; }
         100% { opacity: 1; }
      }

     @keyframes myopacity {
       0%   { opacity: 0; }
       100% { opacity: 1; }
     }
     #elem.show {
       WebkitAnimation : myopacity 1s 1; 
      animation : myopacity 1s 1;     
     }

    var btn = document.getElementById('btn');
    var elem = document.getElementById('elem');
    var timeOutFunc;

    btn.addEventListener('click', function() {
        elem.classList.add('show');
      /*  clearTimeout(timeOutFunc);
        timeOutFunc = setTimeout(function() {
            elem.classList.remove('show')
        }, 1000);*/
    });


    elem.addEventListener('animationend', function(e) {
        console.log('');
        alert('animation ended');
        elem.classList.remove('show')
    });

  <button id="btn">Press Me</button>
   <div id="elem"></div>