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Now this is a very basic Express.js application, arguably not a very beautiful one either but it shows

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us the basic idea behind Express.js and Node.js

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and it gives you an idea of how you work with that and that it is just Javascript with new packages

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you can use which you can't use in the browser

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and with some new built-in modules like this filesystem module used earlier but in the end it's just

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Javascript, just running in a different environment and therefore with a different purpose.

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Now here we're building a traditional web page I'd say, where we render all the HTML pages on the

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server and we return them and there is nothing wrong with that.

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Again I can only point that my complete Node.js guide if you want to learn all about Node.js because

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well that's over 30-hour course,

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there are a lot of topics to cover when it comes to Node.js,

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so here we can of course only scratch the surface.

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Nonetheless I want to dive into one other way of web application, of backend, of server side

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you could build with Node.js.

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Here we got a web application that renders HTML files on the server and sends them back to the client.

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Now if you remember our practice app from earlier, what we did there for example is we got the location

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or the address or the coordinates for certain places on a map from Google's servers,

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we send the request to Google's servers. Now clearly what these servers sent us back was not HTML

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data, it was JSON data which we parsed with this JSON method if you remembered and indeed when sending

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requests from client side Javascript to some server, you typically exchange JSON data because on the

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client side Javascript, you might then have logic that edits the existing HTML page you're on but you

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don't want to replace it entirely with some HTML code sent back by the server, you don't want to reload

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the entire page, you might want to tweak some parts of the page to give the user that highly reactive

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feeling. So therefore this is a server which does not return HTML as our server currently does here

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but instead it returns JSON data and we can of course build such a server too. Why don't we do that and

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connect it here with this little practice application by ensuring that when we create a place there,

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so when we create this share place link, we don't encode all that information here into the link

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but instead we generate an ID for that place on the server side, store that in a database on the server

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side and send that link back to the client side code,

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so to this code and then when a user visits this link which includes that ID thereafter and therefore

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the user ends up on this other index.html file and and so up in the my-place.js file, we parse that ID

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from the URL and again reach out to this backend server here to get the data, the address and the coordinates

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for that ID from our database and then send this data back via JSON or as JSON to this client side

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application so that there we can then render this. Why don't we do it like this,

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this would be a nice practice and that's therefore exactly what we'll do next

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so that we also explore this other way of or this other kind of backend service we could build, also often

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known as an API or specifically, a REST API, an interface we can talk to from any client we want as long

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as we send the correct data to the correct URL.