Change the 404 page

The 404 page cannot be changed dynamically like other pages, although 404.html is changed dynamically in _site. In order for changes to take effect, npm start must be run.

The reason for this is the following code in .eleventy.js:

eleventyConfig.setBrowserSyncConfig({
    callbacks: {
      ready: function(err, browserSync) {
        const content_404 = fs.readFileSync('_site/404.html');
        browserSync.addMiddleware("*", (req, res) => {
          // Provides the 404 content without redirect.
          res.write(content_404);
          res.end();
        });
      },
    },
    ui: false,
    ghostMode: false
  });

This code ensures that _site/404.html is read when npm is started and stored in the browser. So the browser does not re-read 404.html when it is updated.

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