Node.js(express) .end() with JSONP

Question

I have a function like

User.prototype._send = function(type, code, message, callback) {
    if(!message && typeof code != 'number') {
        callback = message;
        message = code;
        code = 200;
    }

    if(typeof message != 'string')
        message = JSON.stringify(message);

    if(type == 'connection' && this.connection) {
        this.connection.writeHead(code || 200, {
            'Content-Type': 'application/json',
            'Content-Length': message.length
        });
        this.connection.end(message);
    } else {
        if(!this.listeners.length)
            return this.message_queue.push(arguments);

        var cx = this.listeners.slice(), conn;
        this.listeners = [];
        while(conn = cx.shift()) {
            conn.writeHead(code || 200, {
                'Content-Type': 'application/json',
                'Content-Length': message.length
            });
            conn.end(message);
        }
        if(callback) callback();
    }
};

It returns JSON to the client now. But I want it to return JSONP. I did a lot of research and tried to replace .end with .jsonp but it does not work.

Answer 1

JSONP("JSON with padding") is a communication technique and is not an another object notation. See http://en.wikipedia.org/wiki/JSONP for more details.

Basically your application need to accept the query parameter jsonp and wrap the json message with that parameter or callback as shown below

var jsonpCallback = req.query.jsonp; //Assuming you are using express

message = JSON.stringify(message);

message = jsonpCallback + "(" + message + ");"