将标记的内容存储在Javascript变量中

I am learning Javascript and I am trying to learn some pretty basic stuff. Basically I have some text in a  tag which I want to append to a variable. However it is not working an I'm not sure why. Any help will be greatly appreciated.

我正在学习Javascript，我正在尝试学习一些非常基本的东西。基本上我在

标签中有一些文本，我想附加到变量。然而它不起作用我不知道为什么。任何帮助将不胜感激。

<html>

<head>
<script type="text/javascript" src="js/jquery.js"> </script>
<script type="text/javascript">
  var x = $('p').html();
  document.write(x);
</script>
</head>

<body>
  <p class="first">Hello World  </p>
</body>

</html>

3 个解决方案

#1

Wrap your code in $.ready handler:

将代码包装在$ .ready处理程序中：

<script type="text/javascript">

$(function(){
  var x = $('p').html();
  document.write(x);
});

</script>

The ready handler fires after DOM has loaded and parsed meaning only then you can maipulate tags (or DOM).

在加载和解析DOM之后，就绪处理程序将触发，这意味着您只能处理标记（或DOM）。

#2

You are running your script before The Hello World is reached in your HTML. Put your script in the body instead just after the  tag:

在HTML中达到

Hello World 之前，您正在运行脚本。将您的脚本放在正文中，而不是在

标记之后：

<html>
    <head>
        <script type="text/javascript" src="js/jquery.js"> </script>
    </head>
    <body> 
        <p class="first">Hello World</p>
        <script type="text/javascript">
            var x = $('p').html();

            document.write(x);
         </script>
    </body>
</html>

You can also use jQuery's ready function like some others have said, but that's an inefficient solution since you already know at which point in the document the  tag is loaded. It's much better to run your script as soon as it's loaded then to wait for the whole document to load using $.ready.

您也可以像其他人所说的那样使用jQuery的ready函数，但这是一个低效的解决方案，因为您已经知道文档中的

标记被加载了。最好在加载后立即运行脚本，然后等待使用$ .ready加载整个文档。

#3

I can't see anything what isn't working (example)

我看不到任何不起作用的东西（例子）

maybe you should write

也许你应该写

jQuery(document).ready(function($){
    //your javascript code
})

but if it doesn't work with that either I should remind you that document.write normally replaces the content

但如果它不起作用，我应该提醒你document.write通常会替换内容

#1