Any one please explain this middleware and i got confusion in middleware

JavaScript
1

const asyncHandler = (fn) => (req, res, next) => {
Promise.resolve(fn(req, res, next)).catch((error) => {
res.status(500).json({ message: error });
});
};

export default asyncHandler;

2

Can you provide some context about where you found this code? It doesn’t look the ExpressJS middleware code we have in the curriculum.

3

It looks like a wrapper function for handling async handlers (sort of promisify type stuff).

Looks similar and has code comments
https://gist.github.com/ZeeshanMukhtar1/ae9e046241a29f4d2d2ed86a5df94ccc

asyncHandler takes a callback fn (presumably a handler) and returns a middleware function (it has next) that when invoked will call the callback with the provided arguments (the parameters of the returned middleware function) and pass the callback return value to resolve. If it throws, it will send a 500 and a JSON response. Or something like that.

4

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