如何阻止Javascript动画文本重复？

Question

我有这段代码可以逐个显示这些字母和单词，但是我的问题是代码仍在重复，有人可以帮助我知道如何停止它吗？

  <div id="changeText"></div> <script type="text/javascript"> var text = ["|", "W|", "We|", "Wel|", "Welc|", "Welco|", "Welcom|", "Welcome|", "Welcome |", "Welcome t|", "Welcome to|", "Welcome to |", "Welcome to K|", "Welcome to Ka|", "Welcome to Kar|", "Welcome to Karl|", "Welcome to Karla|", "Welcome to Karla'|", "Welcome to Karla's|", "Welcome to Karla's |", "Welcome to Karla's T|", "Welcome to Karla's Tr|", "Welcome to Karla's Tra|", "Welcome to Karla's Trad|", "Welcome to Karla's Tradi|", "Welcome to Karla's Tradin|", "Welcome to Karla's Trading|", "Welcome to Karla's Trading", "Welcome to Karla's Trading|", "Welcome to Karla's Tradin|", "Welcome to Karla's Tradi|", "Welcome to Karla's Trad|", "Welcome to Karla's Tra|", "Welcome to Karla's Tr|", "Welcome to Karla's T|", "Welcome to Karla's |", "Welcome to Karla's|", "Welcome to Karla'|", "Welcome to Karla|", "Welcome to Karl|", "Welcome to Kar|", "Welcome to Ka|", "Welcome to K|", "Welcome to |", "Welcome t|", "Welcome |", "Welcome|", "Welcom|", "Welco|", "Welc|", "Wel|", "We|", "W|", "|"]; var counter = 0; var elem = document.getElementById("changeText"); setInterval(change, 250); function change() { elem.innerHTML = text[counter]; counter++; if(counter >= text.length) { counter = 0; } } </script> 

Answer 1

因为您将计数器设置为0，所以会重复。查看掉我的评论后会发生什么。

  <div id="changeText"></div> <script type="text/javascript"> var text = ["|", "W|", "We|", "Wel|", "Welc|", "Welco|", "Welcom|", "Welcome|", "Welcome |", "Welcome t|", "Welcome to|", "Welcome to |", "Welcome to K|", "Welcome to Ka|", "Welcome to Kar|", "Welcome to Karl|", "Welcome to Karla|", "Welcome to Karla'|", "Welcome to Karla's|", "Welcome to Karla's |", "Welcome to Karla's T|", "Welcome to Karla's Tr|", "Welcome to Karla's Tra|", "Welcome to Karla's Trad|", "Welcome to Karla's Tradi|", "Welcome to Karla's Tradin|", "Welcome to Karla's Trading|", "Welcome to Karla's Trading", "Welcome to Karla's Trading|", "Welcome to Karla's Tradin|", "Welcome to Karla's Tradi|", "Welcome to Karla's Trad|", "Welcome to Karla's Tra|", "Welcome to Karla's Tr|", "Welcome to Karla's T|", "Welcome to Karla's |", "Welcome to Karla's|", "Welcome to Karla'|", "Welcome to Karla|", "Welcome to Karl|", "Welcome to Kar|", "Welcome to Ka|", "Welcome to K|", "Welcome to |", "Welcome t|", "Welcome |", "Welcome|", "Welcom|", "Welco|", "Welc|", "Wel|", "We|", "W|", "|"]; var counter = 0; var elem = document.getElementById("changeText"); setInterval(change, 250); function change() { elem.innerHTML = text[counter]; counter++; if(counter >= text.length) { /* counter = 0;*/ } } </script> 

现在，您将得到结果说它是“未定义的”。 显然不是您想要的。 停止此操作的正确方法是在动画结束时取消间隔。

  <div id="changeText"></div> <script type="text/javascript"> var text = ["|", "W|", "We|", "Wel|", "Welc|", "Welco|", "Welcom|", "Welcome|", "Welcome |", "Welcome t|", "Welcome to|", "Welcome to |", "Welcome to K|", "Welcome to Ka|", "Welcome to Kar|", "Welcome to Karl|", "Welcome to Karla|", "Welcome to Karla'|", "Welcome to Karla's|", "Welcome to Karla's |", "Welcome to Karla's T|", "Welcome to Karla's Tr|", "Welcome to Karla's Tra|", "Welcome to Karla's Trad|", "Welcome to Karla's Tradi|", "Welcome to Karla's Tradin|", "Welcome to Karla's Trading|", "Welcome to Karla's Trading", "Welcome to Karla's Trading|", "Welcome to Karla's Tradin|", "Welcome to Karla's Tradi|", "Welcome to Karla's Trad|", "Welcome to Karla's Tra|", "Welcome to Karla's Tr|", "Welcome to Karla's T|", "Welcome to Karla's |", "Welcome to Karla's|", "Welcome to Karla'|", "Welcome to Karla|", "Welcome to Karl|", "Welcome to Kar|", "Welcome to Ka|", "Welcome to K|", "Welcome to |", "Welcome t|", "Welcome |", "Welcome|", "Welcom|", "Welco|", "Welc|", "Wel|", "We|", "W|", "|"]; var counter = 0; var elem = document.getElementById("changeText"); var animation = setInterval(change, 250); function change() { elem.innerHTML = text[counter]; counter++; if(counter >= text.length) { clearInterval(animation); // stop the animation } } </script> 

Answer 2

在此版本中，只有在text中仍然有剩余元素时，才再次调用change 。

 <div id="changeText"></div> <script type="text/javascript"> var text = ["|", "W|", "We|", "Wel|", "Welc|", "Welco|", "Welcom|", "Welcome|", "Welcome |", "Welcome t|", "Welcome to|", "Welcome to |", "Welcome to K|", "Welcome to Ka|", "Welcome to Kar|", "Welcome to Karl|", "Welcome to Karla|", "Welcome to Karla'|", "Welcome to Karla's|", "Welcome to Karla's |", "Welcome to Karla's T|", "Welcome to Karla's Tr|", "Welcome to Karla's Tra|", "Welcome to Karla's Trad|", "Welcome to Karla's Tradi|", "Welcome to Karla's Tradin|", "Welcome to Karla's Trading|", "Welcome to Karla's Trading", "Welcome to Karla's Trading|", "Welcome to Karla's Tradin|", "Welcome to Karla's Tradi|", "Welcome to Karla's Trad|", "Welcome to Karla's Tra|", "Welcome to Karla's Tr|", "Welcome to Karla's T|", "Welcome to Karla's |", "Welcome to Karla's|", "Welcome to Karla'|", "Welcome to Karla|", "Welcome to Karl|", "Welcome to Kar|", "Welcome to Ka|", "Welcome to K|", "Welcome to |", "Welcome t|", "Welcome |", "Welcome|", "Welcom|", "Welco|", "Welc|", "Wel|", "We|", "W|", "|"]; var counter = 0; var elem = document.getElementById("changeText"); function change() { elem.innerHTML = text[counter]; counter++; if (counter < text.length) { setTimeout(change, 250); } } change(); </script> 

顺便说一句，这是一种避免键入"W|" ， "We|" 等等，并使代码更可重用：

 <div id="changeText"></div> <script type="text/javascript"> function animate(elem, text) { var counter = 0; function change() { var length = counter; if (length > text.length) { length = 2 * text.length - counter; } elem.innerHTML = text.substring(0, length) + "|"; counter++; if (counter <= 2 * text.length) { setTimeout(change, 250); } } change(); } animate(document.getElementById("changeText"), "Welcome to Karla's Trading"); </script> 

Answer 3

完成后只需要清除setInterval ：

 <div id="changeText"></div> <script type="text/javascript"> var text = ["|", "W|", "We|", "Wel|", "Welc|", "Welco|", "Welcom|", "Welcome|", "Welcome |", "Welcome t|", "Welcome to|", "Welcome to |", "Welcome to K|", "Welcome to Ka|", "Welcome to Kar|", "Welcome to Karl|", "Welcome to Karla|", "Welcome to Karla'|", "Welcome to Karla's|", "Welcome to Karla's |", "Welcome to Karla's T|", "Welcome to Karla's Tr|", "Welcome to Karla's Tra|", "Welcome to Karla's Trad|", "Welcome to Karla's Tradi|", "Welcome to Karla's Tradin|", "Welcome to Karla's Trading|", "Welcome to Karla's Trading", "Welcome to Karla's Trading|", "Welcome to Karla's Tradin|", "Welcome to Karla's Tradi|", "Welcome to Karla's Trad|", "Welcome to Karla's Tra|", "Welcome to Karla's Tr|", "Welcome to Karla's T|", "Welcome to Karla's |", "Welcome to Karla's|", "Welcome to Karla'|", "Welcome to Karla|", "Welcome to Karl|", "Welcome to Kar|", "Welcome to Ka|", "Welcome to K|", "Welcome to |", "Welcome t|", "Welcome |", "Welcome|", "Welcom|", "Welco|", "Welc|", "Wel|", "We|", "W|", "|"]; var counter = 0; var elem = document.getElementById("changeText"); var setInt = setInterval(change, 250); function change() { elem.innerHTML = text[counter]; counter++; console.log('c:'+counter +'t:'+text.length); if (counter == text.length) { console.log('clear'); clearInterval(setInt); } } </script>