Express: Best way to pass variables to common functions

I have code like this, very simple.

var common = require("./common");
    app.get("/", function(req, res, next) {
    doSomething(req, res);

    if (err) {
        sendError(res, err);
    } else {
        sendResponse(res, values)
    }
});

And these functions are common. They are stored in a separate file.

exports.sendResponse = function(res, values) {
    // do something
    res.json(values);
};

exports.sendError = function(res, err) {
    // do something
    res.json(err);
};

exports.doSomething = function(req, res) {
    // do something, need to access the req and res variables
};

I have a standard output format. So I pass the results to the sendResponse and sendError functions for better handling. It works but I feel a bit silly. The question is, every time I need to pass the res and req parameter to the common functions. Is there a clever way to avoid passing res and req every time?