app.js

var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');

var app = express();
var cors = require('cors')

app.use(cors({credentials: false, origin: true}))
app.options('*', cors())
app.use(function(req, res, next) {
  if (req.method === 'OPTIONS') {
    console.log('!OPTIONS');
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
    res.header("Access-Control-Allow-Methods", "POST, GET, PUT, DELETE, OPTIONS")
    res.header("Access-Control-Allow-Credentials", "true")
    res.writeHead(200, headers);
    res.end();
  }
  next();
});

// if (req.method === 'OPTIONS') {
//       console.log('!OPTIONS');
//       var headers = {};
//       // IE8 does not allow domains to be specified, just the *
//       // headers["Access-Control-Allow-Origin"] = req.headers.origin;
//       headers["Access-Control-Allow-Origin"] = "*";
//       headers["Access-Control-Allow-Methods"] = "POST, GET, PUT, DELETE, OPTIONS";
//       headers["Access-Control-Allow-Credentials"] = false;
//       headers["Access-Control-Max-Age"] = '86400'; // 24 hours
//       headers["Access-Control-Allow-Headers"] = "X-Requested-With, X-HTTP-Method-Override, Content-Type, Accept";
//       res.writeHead(200, headers);
//       res.end();
// } else {
// //...other requests
// }

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', indexRouter);
app.use('/users', usersRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;