CODEWITHSUNDEEP
javascriptnode.js
Dan
Dan

Reputation: 175

Node.js callback type error with http.createServer

I am very new to node.js, and was playing around with a few tutorials and stumbled across this problem doing a little refactoring.

The tutorial I was following is linked here: http://www.tutorialspoint.com/nodejs/nodejs_web_module.htm

I decided to split out the callbacks to make the code a little more readable, so created a file reader method and a 'monitor' method:

function monitor(request, response)
{
        var pathname = url.parse(request.url).pathname;

        fs.readFile(pathname.substr(1), reader() );
}

http.createServer(monitor()).listen(8080);

When I run this I get the following error:

    var pathname = url.parse(request.url).pathname;
                                    ^

TypeError: Cannot read property 'url' of undefined
    at monitor

Clearly this is a type issue. I was looking into casting to http.incomingMessage, but am not familiar enough with javascript and my web searching did not yield a quick solution.

Thanks!

Upvotes: 1

Views: 839

Answers (1)

M. Damian Mulligan
M. Damian Mulligan

Reputation: 869

Your problem is in this line:

http.createServer(monitor()).listen(8080);

It should be:

http.createServer(monitor).listen(8080);

The reason is because you want to pass the monitor function as a callback, not call it. Placing the parenthesis after monitor will call the function with no arguments. When arguments are not given to the function, they take on the value undefined, hence the error you're getting.

Upvotes: 5

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