Question

我不知道为什么这个简单的代码虽然它是出于教育目的所以，请帮助我找出我做错的事情：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
                "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>Random thoughts part one</title>
    <meta http-equiv="content-type" content="text/html;charset = utf-8" />
    <meta name="keywords" content="thoughts, random, philosophy, mohamed, samir ,sameer, muhammad , mohammed samir" />
    <meta name="description" content="This is a personal page about Mohamed Samir khalil that contain his thoughts and believes" />
    <link rel="stylesheet" type="text/css" href="style.css">
      <body>
        <script type="text/javascript">//
            <![CDATA[

                    alert("hello");
                    var target = document.getElementById("unique_element");
                    alert(target.length);
            //]]>
        </script>
        <center>
          <h3>Random thoughts</h3>
        </center>
        <p id="unique_element">I do not think it is coincidence, because every time I walk in streets I have that strong feeling that keeps telling me &#8221;Man, you have to help people!&#8221;.</p>
        <p>In the beginning I thought that because of thinned for recognition I mean I do this just to hear people say &#8220;thank you&#8221; and to hear people say &#8220;it is great thing that you
        are between us&#8221; so I thought it is all about ego, but you know when I really realized that it is not about ego!</p>
        <p>I realized that when I helped someone and they did not say thank you, what was supposed to happen is that , I should feel anger because it is all about ego, right?</p>
        <p>But what really happened that I felt happy just to help now people who are reading this will say either &#8220;you are so kind&#8221; or &#8220;Okay, you want to make it up huh!&#8221;but
        the reality is just neither this or that ; actually I realized that I am helping people because this is what make us humans and this thing let us feel that we are not alone in this world so
        it is kind of socializing too and also when you help people, I guarantee that someday someone will help you in a very tough situation and he or she will come out of nowhere this is the rule
        of life and this is how people should live.</p>
      </body>
    </link>
  </head>
</html>

Answer 1

您的脚本在解析DOM之前运行：

var target = document.getElementById("unique_element");

不会返回HTML元素，而target.length只会失败。尝试将JavaScript部分放在结束</body> - 标记之前。

Answer 2

您正在尝试显示DOM元素的长度。请改为alert(target.innerHTML.length);。

无法运行第二个警报

2 个答案: