So for some reason this unobtrusive 开发者_如何学Pythonjavascript code is not working and I can't figure out for the life of me why it won't work.
I dynamically change the className of a div element and therefore I expect the CSS to reflect that change. However it doesn't. Here's the simplified code.
html:
<head>
<title>Your Page</title>
<link rel="stylesheet" type="text/css" href="style.css" />
<script type="text/javascript" src="us.js"></script>
</head>
<body>
<div id="wrapper">
<h1 id="title">Your Page</h1>
</div>
</body>
javascript:
window.onload = function() {
document.getElementById("wrapper").className = "2";
}
css:
#wrapper{
background-color: white;
}
#wrapper.1 {
background-color: black;
}
#wrapper.2 {
background-color: red;
}
#wrapper.3 {
background-color: blue;
}
I look at the wrapper div in firebug and it shows the class being changed to "2". However, the webpage doesn't reflect that by changing the background color to be red. (it doesn't work with changing text color either. I tried that.). I know the CSS is correctly loading. So what is the problem?
Your css class names need to begin with a letter, like this:
#wrapper.num1 {
background-color: black;
}
#wrapper.num2 {
background-color: red;
}
#wrapper.num3 {
background-color: blue;
}
2 is an invalid class name. Your class name cannot be a number; it must be an alphanumeric string starting with a letter.
Did you try using a different class name? Check Which characters are valid in CSS class names/selectors? . css class names cannot start with numbers.
![Interactive visualization of a graph in python [closed]](https://www.devze.com/res/2023/04-10/09/92d32fe8c0d22fb96bd6f6e8b7d1f457.gif)
加载中,请稍侯......
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