'When doing a booking system, where would it be better to do? Back end or front end

My question is, I'm creating a react native application. I'm using mongoose, expressjs, nodejs, and mongodb. I am debating if to do the logic in front end or back end, where would it be ideal? I fell like back-end since it would be great in case I want to create a reactjs project in the future. What do you guys think? Example of what I want is display available times of the day where a user could purchase a service and each service has a time set. For example, if you purchase a service for a food and the time to create it takes 30 mins, then chef has that time unavailable.



Solution 1:[1]

You must be aware that the frontend can always be manipulated by users. For example, properly pressing the "Order" button in your app may lead to a request

POST /Order?Food=IrishStew&Price=11

but a malicious can change that request to

POST /Order?Food=IrishStew&Price=1

and you would have to validate the price in the backend before accepting the order.

Summary: The frontend offers convenience for users, but every logic (for example, the price determination) that matters to the service company must be implemented in the backend.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 Heiko Theißen