"Another idea which was suggested by SCdF would be to append a bogus query string to the file. (Some Python code to automatically use the timestamp as a bogus query string was submitted by pi.) However, there is some discussion as to whether or not the browser would cache a file with a query string. (Remember, we want the browser to cache the file and use it on future visits. We only want it to fetch the file again when it has changed.) Since it is not clear what happens with a bogus query string, I am not accepting that answer."

<link rel="stylesheet" href="file.css?<?=hash_hmac('sha1', session_id(), md5_file("file.css")); ?>" />

哈希文件意味着当文件发生变化时，查询字符串也会发生变化。如果没有，它将保持不变。每个会话也强制重新加载。

此外，您还可以使用重写使浏览器认为它是一个新的URI。

对于开发:使用浏览器设置:例如，Chrome网络选项卡有一个禁用缓存选项。

对于生产:使用服务器端呈现框架或纯JavaScript代码将唯一的查询参数附加到请求(例如，q?Date.now())。

// Pure JavaScript unique query parameter generation
//
//=== myfile.js

function hello() { console.log('hello') };

//=== end of file

<script type="text/javascript">
    document.write('<script type="text/javascript" src="myfile.js?q=' + Date.now() + '">
    // document.write is considered bad practice!
    // We can't use hello() yet
</script>')

<script type="text/javascript">
    hello();
</script>

这个解决方案是用PHP编写的，但是应该很容易适应其他语言。

原始的.htaccess正则表达式可能会导致json-1.3.js等文件出现问题。解决方案是只有在结尾恰好有10位数字时才重写。(因为10位数字涵盖了从2001年9月9日到2286年11月20日的所有时间戳。)

首先，我们在.htaccess中使用下面的重写规则:

RewriteEngine on
RewriteRule ^(.*)\.[\d]{10}\.(css|js)$ $1.$2 [L]

现在，我们编写以下PHP函数:

/**
 *  Given a file, i.e. /css/base.css, replaces it with a string containing the
 *  file's mtime, i.e. /css/base.1221534296.css.
 *
 *  @param $file  The file to be loaded.  Must be an absolute path (i.e.
 *                starting with slash).
 */
function auto_version($file)
{
  if(strpos($file, '/') !== 0 || !file_exists($_SERVER['DOCUMENT_ROOT'] . $file))
    return $file;

  $mtime = filemtime($_SERVER['DOCUMENT_ROOT'] . $file);
  return preg_replace('{\\.([^./]+)$}', ".$mtime.\$1", $file);
}

现在，无论你在哪里包含你的CSS，从下面更改它:

<link rel="stylesheet" href="/css/base.css" type="text/css" />

:

<link rel="stylesheet" href="<?php echo auto_version('/css/base.css'); ?>" type="text/css" />

这样，您就不必再次修改链接标签，用户将始终看到最新的CSS。浏览器将能够缓存CSS文件，但当您对CSS进行任何更改时，浏览器将看到这是一个新的URL，因此它不会使用缓存的副本。

这也适用于图像、favicons和JavaScript。基本上任何不是动态生成的东西。

我在为我的SPA寻找解决方案时遇到了这个问题，它只有一个列出所有必要文件的index.html文件。虽然我得到了一些帮助我的线索，但我找不到一个快速而简单的解决方案。

最后，我编写了一个快速页面(包括所有代码)来自动版本HTML/JavaScript index.html文件，作为发布过程的一部分。它工作完美，只更新新文件根据日期最后修改。

你可以在Autoversion your SPA index.html上看到我的文章。还有一个独立的Windows应用程序。

代码的核心是:

private void ParseIndex(string inFile, string addPath, string outFile)
{
    string path = Path.GetDirectoryName(inFile);
    HtmlAgilityPack.HtmlDocument document = new HtmlAgilityPack.HtmlDocument();
    document.Load(inFile);

    foreach (HtmlNode link in document.DocumentNode.Descendants("script"))
    {
        if (link.Attributes["src"]!=null)
        {
            resetQueryString(path, addPath, link, "src");
        }
    }

    foreach (HtmlNode link in document.DocumentNode.Descendants("link"))
    {
        if (link.Attributes["href"] != null && link.Attributes["type"] != null)
        {
            if (link.Attributes["type"].Value == "text/css" || link.Attributes["type"].Value == "text/html")
            {
                resetQueryString(path, addPath, link, "href");
            }
        }
    }

    document.Save(outFile);
    MessageBox.Show("Your file has been processed.", "Autoversion complete");
}

private void resetQueryString(string path, string addPath, HtmlNode link, string attrType)
{
    string currFileName = link.Attributes[attrType].Value;

    string uripath = currFileName;
    if (currFileName.Contains('?'))
        uripath = currFileName.Substring(0, currFileName.IndexOf('?'));
    string baseFile = Path.Combine(path, uripath);
    if (!File.Exists(baseFile))
        baseFile = Path.Combine(addPath, uripath);
    if (!File.Exists(baseFile))
        return;
    DateTime lastModified = System.IO.File.GetLastWriteTime(baseFile);
    link.Attributes[attrType].Value = uripath + "?v=" + lastModified.ToString("yyyyMMddhhmm");
}

我已经通过使用解决了这个问题 ETag:

ETag或实体标签是HTTP的一部分，HTTP是万维网协议。它是HTTP为Web缓存验证提供的几种机制之一，这种机制允许客户机发出有条件的请求。这使得缓存更加高效并节省带宽，因为如果内容没有更改，Web服务器不需要发送完整的响应。ETags还可以用于乐观并发控制，1作为一种帮助防止资源的同步更新相互覆盖的方法。

I am running a Single-Page Application (written in Vue.JS). The output of the application is built by npm, and is stored as dist folder (the important file is: dist/static/js/app.my_rand.js) Nginx is responsible of serving the content in this dist folder, and it generates a new Etag value, which is some kind of a fingerprint, based on the modification time and the content of the dist folder. Thus when the resource changes, a new Etag value is generated. When the browser requests the resource, a comparison between the request headers and the stored Etag, can determine if the two representations of the resource are the same, and could be served from cache or a new response with a new Etag needs to be served.

感谢Kip的完美解决方案!

我对它进行了扩展，将其用作Zend_view_Helper。因为我的客户端在虚拟主机上运行他的页面，我也为此扩展了它。

/**
 * Extend filepath with timestamp to force browser to
 * automatically refresh them if they are updated
 *
 * This is based on Kip's version, but now
 * also works on virtual hosts
 * @link http://stackoverflow.com/questions/118884/what-is-an-elegant-way-to-force-browsers-to-reload-cached-css-js-files
 *
 * Usage:
 * - extend your .htaccess file with
 * # Route for My_View_Helper_AutoRefreshRewriter
 * # which extends files with there timestamp so if these
 * # are updated a automatic refresh should occur
 * # RewriteRule ^(.*)\.[^.][\d]+\.(css|js)$ $1.$2 [L]
 * - then use it in your view script like
 * $this->headLink()->appendStylesheet( $this->autoRefreshRewriter($this->cssPath . 'default.css'));
 *
 */
class My_View_Helper_AutoRefreshRewriter extends Zend_View_Helper_Abstract {

    public function autoRefreshRewriter($filePath) {

        if (strpos($filePath, '/') !== 0) {

            // Path has no leading '/'
            return $filePath;
        } elseif (file_exists($_SERVER['DOCUMENT_ROOT'] . $filePath)) {

            // File exists under normal path
            // so build path based on this
            $mtime = filemtime($_SERVER['DOCUMENT_ROOT'] . $filePath);
            return preg_replace('{\\.([^./]+)$}', ".$mtime.\$1", $filePath);
        } else {

            // Fetch directory of index.php file (file from all others are included)
            // and get only the directory
            $indexFilePath = dirname(current(get_included_files()));

            // Check if file exist relativ to index file
            if (file_exists($indexFilePath . $filePath)) {

                // Get timestamp based on this relativ path
                $mtime = filemtime($indexFilePath . $filePath);

                // Write generated timestamp to path
                // but use old path not the relativ one
                return preg_replace('{\\.([^./]+)$}', ".$mtime.\$1", $filePath);
            } else {
                return $filePath;
            }
        }
    }
}