2) The Express JS application

Structure

The Express code is present in the following folders:

• /views/*.ejs : Qwant Maps HTML templates (index page, error pages)
• /bin/*.js : entry point (index.js / app.js), helpers and middlewares

Middlewares

The middlewares intercept the requests from/to Qwant Maps to:

• detect the browser and redirect the user if needed
• interpret some query strings server-side
• add metadata
• ...

Hot take: a middleware needs 3 parameters (req, res, next) and calls next() after doing its job. (unless it does an early error or a redirection)

HotLoadPoi

• If a PoI is present in the URL when the application loads, prefetch_poi.js loads the item and copies its data in a <script> tag of the index page.
• The PoI data is stored in window.hotLoadPoi
• Possible enhancement: use this PoI as initial value in poiContext ?