Express Middleware to Disable Gatsby's window.replaceState()

express-middleware-disable-gatsby-window-replacestate.ts

// Express middleware to disable Gatsby window.replaceState() to
// avoid changing new rewritten URLs back to original URLs
// https://github.com/gatsbyjs/gatsby/blob/c91ed287fd319a345c2f27877e20656826767e92/packages/gatsby/cache-dir/production-app.js#L159-L187

const appJsFilePath = existingGatsbyFiles.find((filePath) =>
  /^\/app-[\da-f]+\.js$/.test(filePath),
)!;
const appJsContent = readFileSync(
  join(websitePath, 'public', appJsFilePath),
  'utf-8',
);

app.use((req, res, next) => {
  if (req.url === appJsFilePath) {
    res.type('application/javascript');
    res.send(
      appJsContent.replace(
        'const{pagePath:f,location:m}=window;f&&""+f!==m.pathname+(f.includes("?")?m.search:"")&&!(Z.findMatchPath((0,A.Z)(m.pathname,""))||f.match(/^\\/(404|500)(\\/?|.html)$/)||f.match(/^\\/offline-plugin-app-shell-fallback\\/?$/))&&(0,a.navigate)(""+f+(f.includes("?")?"":m.search)+m.hash,{replace:!0});',
        // Changed `""+f+` (Gatsby pagePath) to `""+m.pathname+` (window.location.pathname)
        'const{pagePath:f,location:m}=window;f&&""+f!==m.pathname+(f.includes("?")?m.search:"")&&!(Z.findMatchPath((0,A.Z)(m.pathname,""))||f.match(/^\\/(404|500)(\\/?|.html)$/)||f.match(/^\\/offline-plugin-app-shell-fallback\\/?$/))&&(0,a.navigate)(""+m.pathname+(f.includes("?")?"":m.search)+m.hash,{replace:!0});',
      ),
    );
    return;
  }

  next();
});