I dont understand what "module.exports.get = get;" does? Can someone please elaborate?

Question

I dont understand what "module.exports.get = get;" does?

Can someone please elaborate on what this does and why I need it?

Why does the code not execute without it?

Thanks!

app.js:

var profile = require("./profile.js");
profile.get("jeffward2");

profile.js:

//Problem: we need a simple way to look at a user's badge count and Javascript points
//Solution: Use node.js to connect to Treehouse's API to get progile information and print out

var http = require("http");

//Print out message
function printMessage(username, badgeCount, points) {
    var message = username + " has " + badgeCount + " total badge(s) and " + points + " points in JavaScript.";
    console.log(message);
}

//Print out Error messages
function printError(error) {
    console.error(error.message + "<----  error has occured!. Oh Nooz!");
}

function get(username) {
//Connect to API URL (https://teamtreehouse.com/username.json)
var request = http.get("http://teamtreehouse.com/" + username + ".json", function (response) {
    var body = "";
    //Read the data
    response.on('data', function (chunk) {
        body += chunk;
    });
    response.on("end", function () {
        if (response.statusCode === 200) {
            try {
                //Parse the data
                var profile = JSON.parse(body);
                //Print the data out
                printMessage("jeffward2", profile.badges.length, profile.points.JavaScript);
            } catch (error) {
                //Parese Error
                printError(error);
            }
        } else {
            printError({
                message: "There was an error getting the profile for " + username + ". (" + http.STATUS_CODES[response.statusCode] + ")"});
        }

    });
});
    //Check for connection error
    request.on("error", printError);
}

module.exports.get = get;

Answer 1 · 2015-08-23T20:08:36Z

August 23, 2015 8:08pm

In your app.js file you used a function get (profile.get("jeffward2");) written in another file - profile.js. By export, you've allowed function get from profile.js to be used in app.js. Without it, by just requiring file profile.js, you wouldn't be able to call it in app.js.

Answer 2 · 2016-01-13T13:49:24Z

January 13, 2016 1:49pm

Just in case anyone checks this question out, you can imagine this line:

var profile = require("./profile.js");

As jamming the entire contents of 'profile.js' into the variable profile. So to access anything in the variable profile, you need to do 'profile.x' similar to when you create an object and want to access any properties or variables.

'module.exports.x = x' is a line that just says that we want to make the the right side available for access, and not just hidden inside of 'profile'.

Answer 3 · 2015-08-23T20:15:40Z

August 23, 2015 8:15pm

Yes :)

Answer 4 · 2015-08-24T12:42:40Z

August 24, 2015 12:42pm

Just a heads up, I was trying to explain this to myself as well.

How I manged to understand it as I thought of it as being the same concept used in the prototypal inheritance, when working with creator function in JavaScript. Not quite sure if you did that course already here on TreeHouse, but basically you're "prototyping" the method that can be shared across all of the instances of an object, created through that same creator function.

If you went through that course, I think you'll be able to find the same analogy I followed, or it's just how I understood it; judging by the akak's response, it seems like that it's not that far from the truth = ). As in both, you're exporting the method to be used either on another instance of that object, or in this case on a module that you're requiring (with require() ) later on or in other file.

I'm used to learning things this way, as it helps me remember much easier and at the same time I'm relearning the concepts from before, that I perhaps forgot by the time.

Cheers! And happy coding

Update: After watching the video for the second time I've came to one more conclusion on my own, on why the methods on the module must be exported (I am not saying it's 100% correct, but it just helped me understand it better and it will perhaps someone else too!).

When we're programming on the web, more particularly for the web browser (javascript code that will get executed on the client side) we have HTML document in which we're linking to the javascript files (by using script tags), which allows us to use a code from one javascript file, inside of another, ONLY if the javascript file from which we're requiring the code (functions, variables, etc) is linked first. To explain it little further, a simple example we're all familiar with would look like this:

<script src="jQuery.js"></script>
<script src="app.js"></script>

So if we want to use the jQuery methods in our code, we must link to the jQuery library first, before we link to our own app.js file. Since the Node is a console driven and there's no HTML in which we actually do link the javascript files in following a certain order, we need to explicitly say that we want to use a function (aka method) from one file in our other files, which the module.exports.methodName will actually allow us to.

Correct me if I'm wrong please, since I don't want to be posting inaccurate data =p. Hope that helps.

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Jeff Ward

Jeff Ward

I dont understand what "module.exports.get = get;" does? Can someone please elaborate?

Chyno Deluxe

Chyno Deluxe

4 Answers

akak

akak

Jeff Ward

Jeff Ward

Jarrad O'Brien

Jarrad O'Brien

akak

akak

Ognjen Jevremovic

Ognjen Jevremovic