How to get process list in mongodb using nodejs?

I am using node js as front end and mongodb is as backend. I got successfull connection. But while trying to get all the process running in mongodb are throw error. My code is below.

var Db = require('mongodb').Db, Server = require('mongodb').Server;
        var db = new Db('admin', new Server(conf.host, conf.port));
        db.open(function(err, db1) {
            var adminDb = db1.admin();
            adminDb.authenticate(conf.user, conf.password, function(err, result) {
                if(result == true) {
                     var obj = adminDb.currentOp({"active":true});
                     console.log("output="+output);
                }

            });
    });

I am getting below error.

TypeError: adminDb.currentOp is not a function

via selvan