Node js throw exception in events-CodePudding

I am wondering how to throw an error or returning value from event.

My code looks like this:

    _initConnection(){
        try{
            const errorValidation = this.errorValidation
            const HOST = "192.168.2.32"
            const PORT = 8282
            this.socket = net.createConnection(PORT, HOST)
            this.socket.on('data', function(data) {
                errorValidation(data)// throwing error
                console.log('Received: '   data);
                return data
            });
            this.socket.on('err', function(err) {
                console.log('Connection' err);
            });
            this.socket.on('close', function(e) {
                console.log('Connection closed');
                
            });
        }catch(err){
            throw err
        }
    }

But because of the event throwing error is impossible it crash the app what should I do? Is using a Promies is a good guess?

CodePudding user response：

Your problem is, essentially, the same as How do I return the response from an asynchronous call?.

In your try/catch block you assign a function which will run, in the future, whenever there is a data event.

The try/catch block then finishes (as does the function it is inside).

Later, in the future, you want to throw an exception, but you can't catch it in the try/catch block you had because it doesn't exist any more. The security guard watching for trouble has packed up and gone home.

If you want to handle errors relating to the data event, then you need to do it inside the function that runs when there is a data event. It is the only thing available to do that at the right time.

CodePudding user response：

You can throw error like this in catch block.

throw new Error('some error message')

Refer docs for error handling in express