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Babel includes JSX processing.

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                <!DOCTYPE html>


  <style type="text/css">
    #divTyping {
      width: 300px;
      height: 25px;
      border: 2px solid #dddddd;
      margin: 100px auto;

<!-- js 实现自动打字效果 -->

  <div id="divTyping"></div>

  <script type="text/javascript">
    var str = "js 实现自动打字效果  的简单实现";
    var i = 0;

    function typing() {
      var divTyping = document.getElementById("divTyping");
      if (i <= str.length) {
        // str.slice(start, end) 切片函数,切取数组中的从start到end的字符串,不修改原数组
        // start 参数必须要有,end 可以没有,默认数组最后一个
        divTyping.innerHTML = str.slice(0, i++) + "_";
        setTimeout("typing()", 200); // 递归调用
      } else {
        divTyping.innerHTML = str; // 结束打字,移除光标
    // 该函数实际上不是一个个输出,只是后面的长度多一的字符串覆盖前面的字符串