server.js

var express = require("express");
var app = express();
var yaml = require("yamljs");
var fs = require("fs");
var refParser = require("json-schema-ref-parser");
var args = process.argv.slice(2);

app.get("/", function (req, res) {
  res.sendFile(__dirname + "/local.html");
});

app.get("/openapifile", function (req, res) {
  if (args[0] == "json") {
    fs.readFile("openapi.json", "utf8", function (err, data) {
      var json = JSON.parse(data);
      if (err) throw err;
      refParser.dereference(json, function (err, schema) {
        if (err) {
          console.error(err);
        } else {
          res.send(schema);
        }
      });
    });
  } else {
    fs.readFile("openapi.yml", "utf8", function (err, data) {
      if (err) throw err;
      var json = yaml.parse(data);
      refParser.dereference(json, function (err, schema) {
        if (err) {
          console.error(err);
        } else {
          res.send(schema);
        }
      });
    });
  }
});

app.listen(3001, function () {
  console.log("listening on http://localhost:3001");
});