Questions: Express next() parameter in a function

[khafidprayoga]

When i built auth app

My middlewares:

• protected (for check token)
• controllers (to validate body data and interact with services)
• exceptions (sent error status to client if internal error thrown)

when i use next(id) on protected middleware it throws and error and skip controllers.
It goes to exceptions middleware (skip the controllers). In my case i need pass id to the expected contollers but it gives error.

and work excatly as expected, when i change my code to

try{
    const {id} = await verifyToken()
    req.id = id
    next()
}catch(error){
    next(error)
}

My question:
if i pass a parameter to next() interface, does it redirect to express internal error handler? even if i dont use try-catch statements

[dougwilson]

Hello, and sorry you are having an issue. When writing a middleware function, the function is called with three arguments: req, res, and next. The next argument is a function for your middleware to call if it wants to proceed to the next middleware, if any. It takes a since argument of an error. If you provide an error argument to the next function, it will skip forward to your next error handling middleware, if any.

You can find out more on our website at http://expressjs.com/en/guide/writing-middleware.html and http://expressjs.com/en/guide/error-handling.html

I hope this helps!

[khafidprayoga]

@dougwilson ok noted! any passed parameter to next interface is an error

[khafidprayoga]

if i need to pass request data i should add object properties on request interface

[khafidprayoga]

Thanks!

[dougwilson]

Yep!