marko/src/express.js

require("./");

var express = module.parent
  ? module.parent.require("express")
  : require("express");

patchResponse(express.response);
delete require.cache[__filename];

module.exports = function markoAppMiddleware() {
  var sacrificialApp = express();

  sacrificialApp.once("mount", function onmount(parent) {
    // Patch the response
    patchResponse(parent.response);

    // Remove sacrificial express app
    if (parent._router) {
      // Support Express <= 4.x
      parent._router.stack.pop();
    } else {
      // Support express 5.x
      parent.router.stack.pop();
    }
  });

  return sacrificialApp;
};

function patchResponse(response) {
  response.marko =
    response.marko ||
    function(template, data) {
      if (typeof template === "string") {
        throw new Error(
          "res.marko does not take a template name or path like res.render.  " +
            "Instead you should use `require('./path/to/template.marko')` " +
            "and pass the loaded template to this function."
        );
      }

      var res = this;
      var req = res.req;
      var app = res.app;
      var $global = Object.assign({ app, req, res }, app.locals, res.locals);

      if (data) {
        data = Object.assign(data, {
          $global: Object.assign($global, data.$global)
        });
      } else {
        data = { $global };
      }

      res.set({ "content-type": "text/html; charset=utf-8" });
      return template.render(data, res).on("error", req.next);
    };
}