Console gives me Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client

Question

I don't know how to fix this error.

But when I send data through PostMan, it saves everything well and does its job, but I get this error on the console. If I remove the .json(table).end() it works.

export const build_tab = async (req : express.Request , res : express.Response ) => { try{ const { seats, number } = req.body ;

    if(!seats||!number){
       return res.sendStatus(400);
    }
    const _id = require('uuid').v4() ;
   
    const table = await createTable({
        _id,
        number,
        seats
    });

    return res.sendStatus(200).json(table).end();
}
catch(error){
   console.log(error)         ;
   return res.sendStatus(400) ;
}

}

Answer 1

res.sendStatus(<code>) isn't meant to be chained with any other express functions because it sets the status and sends a response body all by itself. See the documentation:

Sets the response HTTP status code to statusCode and sends the registered status message as the text response body. If an unknown status code is specified, the response body will just be the code number.

Therefore, if you want to send a custom json body, don't use .sendStatus(). Instead, just use something like:

return res.status(200).json(table)

Note that you don't need to follow .json(...) with .end(). Here is the documentation for .end():

Use to quickly end the response without any data. If you need to respond with data, instead use methods such as res.send() and res.json().