How do I know which parameters I should use in NodeJS

Question

I'm trying to learn every aspect of nodeJS and I was following this tutorial I tried to look at express and node's documentation but it doesn't explain what I want to know.

How do you know which parameters does a function pass?

Here's an example:

How do you know this returns a router?

module.exports = function(router) {

// http:localhost:3000/users

router.post('/users', function(req, res){
    var user = new User();
        user.username = req.body.username;
        user.password = req.body.password;
        user.email = req.body.email;
        if (req.body.username == null || req.body.username == '' || req.body.password == null || req.body.password == '' || req.body.email == null || req.body.email == ''){
            res.send('Ensure username, email and password were provided');
        } else {
            user.save(function(err){
                if (err) {
                    res.send(' Username/email already exists ');
                }   else {
                    res.send('User created ')
                }
            });
        }
});
/*console.log(router);
return router;*/
}

PS. I know I'm using router.post but how can I know that. PS2. I think it's not the same question as the one asking about JS.

RTFM. No seriously, in JS there is no typing so you can’t know the object you’re looking at is a rooter without looking at it first. For this you can simply `console.log` the object and you’ll see it’s attributes. — Ulysse BN, Feb 08 '17 at 04:22
Side-remark: [both `null` and `''` are falseys](http://stackoverflow.com/a/19839953/1022914) in JavaScript -- meaning you can just do `if (!req.body.username || !req.body.password || ...)` — Mikey, Feb 08 '17 at 04:26

score 1 · Answer 1 · answered Feb 08 '17 at 04:22

1

You should have a look at the Express docs. Also, debugging your app could be a good start.

Edited: As others mention, you can simply use console.log.

answered Feb 08 '17 at 04:22

quanfoo

365
2
9

I am using `console.log()` I just commented it and I looked at the Express docs but I can't find it. I said that in the post... – Diego Rios Feb 08 '17 at 04:26
1

Don't use console.log for debugging on anything but the most trivial applications. Get used to using node-inspector or some other runtime debugging tool. – Paul Feb 08 '17 at 04:50

score 0 · Answer 2 · answered Feb 08 '17 at 04:48

0

It's very helpful when using IDE support live code hints. For myself, I use VScode. It's save me a lot of time by showing code hints timely. I no longer need to search document whenever using them.

answered Feb 08 '17 at 04:48

Albert

94
7

score 0 · Answer 3 · answered Feb 08 '17 at 05:27

I think I got it.

This function:

router.post('/users', function(req, res){
var user = new User();
    user.username = req.body.username;
    user.password = req.body.password;
    user.email = req.body.email;
    if (req.body.username == null || req.body.username == '' || req.body.password == null || req.body.password == '' || req.body.email == null || req.body.email == ''){
        res.send('Ensure username, email and password were provided');
    } else {
        user.save(function(err){
            if (err) {
                res.send(' Username/email already exists ');
            }   else {
                res.send('User created ')
            }
        });
    }
});

is a route method (router).

Routing refers to determining how an application responds to a client request to a particular endpoint, which is a URI (or path) and a specific HTTP request method (GET, POST, and so on).

I could've put any name instead of router and it would've still work because it is returning the router method.

How do I know which parameters I should use in NodeJS

3 Answers3