nodejs inherit function inside a function - node.js

Question

im trying to inherit a function inside one, but im not sure how.
function register(Username, Password, callback)
{
var result;
UserModel.findOne({username: Username}, function(error, data)
{
if(error)
console.log(error);
if(data)
result = 'already exist';
mongoose.connection.close();
if(!data)
{
var user = new UseModel(
{
username: Username,
password: Password
});
user.save(function(error)
{
if(error)
{
console.log(error);
result = 'Error';
}
result = 'success';
mongoose.connection.close();
});
}
});
callback;
}
i thought that making a callback, i would be able to set a custom function in there.
i've seen someplaces that people do inherit functions inside another one, but i dont find them anymore and im trying to do them, for this code im saving a record in mongo.
so lets just say, in the other code, im calling this function with first 2 parameters, and the third would do the function i want it to do depending of the result, just like this.
this.register('myname', 'mypassword', function(
{
if(result != 'error')
{
response.render('register',
{
'Title': Title,
'result': result
});
}
}));
im not sure if the inherit is like this. but this is what im trying to do, im learning js with node so please sorry about my unexperience.
PD: im using express, swig, body-parser and mongoose modules for node.js

Answer 1

Here's how your register() function might look:
function register(Username, Password, callback)
{
UserModel.findOne({username: Username}, function(error, data)
{
if(error)
return callback(error);
if(data)
return callback(null, 'User already exists');
var user = new UseModel(
{
username: Username,
password: Password
});
user.save(function(error)
{
if(error)
return callback(error);
callback(null, 'Success');
});
});
}
Here's how it would be used:
this.register('myname', 'mypassword', function(error, result)
{
if (error)
return console.error(error); // do something better here
response.render('register',
{
'Title': Title,
'result': result
});
});