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JavaScript

Posted by Jason Pallone
Jason Pallone
11,340 Points

How do front-end and back-end communicate?

So if I write an express app and I want to access it in the frontend , how do I do that?

If I write a frontend app, how do I access it in express?

Like for example i create a blog site, and I have a sign up form that I want to use AJAX on, so the user can sign up for newsletters and then the form hides, without having to reload the page. How would the front end and back end work to do that? Like code wise, do I need to import like we do routes in express? Etc..

This has me confused so any help is appreciated! Thanks!

2 Answers

Aayush Mitra
Aayush Mitra
24,904 Points

Hello again!

So basically you make your routes in express. Eg app.get() app.post() etc. If we had a route like:

app.get('/api/main', (req, res) => {
  res.json({hi: "hi"});
});

If you were to go to http://localhost:port/main, it would return: {hi: “hi”}

So all you do is in your front end JavaScript with either Ajax or fetch api, you make an HTTP request to http://localhost:port/main/ and it would return the json data back and you could store that into a variable. Then, you could use that data inside the JavaScript object literal and insert it into the HTML in the front end JavaScript.

I hope this helps! If this does not make sense, please reply.

Thanks :)

Jason Pallone
Jason Pallone
11,340 Points

Ok most of that makes sense, so what about when like you have a user login option and they go to login, you would get their login info from a database right?(if they already signed up) If so, would that be just by express handling all of that, or does front end work come in too ?

Aayush Mitra
Aayush Mitra
24,904 Points

Express handles all of it.

Jason Pallone
Jason Pallone
11,340 Points
Jason Pallone
Jason Pallone
11,340 Points

Thanks for info! That clears it up a bit for me!