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Carlos Casciano
10,459 PointsWhy does response on the function refers to the https get?
Hi!
In the code below, I don´t understand why 'res' in the anonymous function refers to the data inside the https we are getting, what is the logic here? Is it a simple response from the server that I am receiving? Is it a keyword in this case?
https.get("https://teamtreehouse.com/" + username + ".json", function(res){
console.dir(res.statusCode);
})
Ty,
1 Answer
Casey Ydenberg
15,622 PointsBasically, .get is a function which accepts two parameters. The second parameter is a callback function that explains what to do when a response is received. Whenever Node receives a response, it will call the function that was passed to it when .get is run.
By definition, the first parameter passed to that callback will be the response from the remote server. You can name it whatever you like: replace res with foo in the code above and it will still work.
Now you might be wondering, why doesn't https.get just return the response from the server? In PHP you can just go
<?php
$res = file_get_contents('https://whatever');
?>
which looks a lot cleaner.
This is Node's asynchronous nature. The Node interpreter can't just wait at a specific line of code until it gets a response from somewhere else. So https.get can't just return a value (Well it can, but not a value that means what you think it does) because it won't have a value a the time that the request is fired off. To get around this, you don't expect a value, you pass in a function that explains what to do when the response comes back.