StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
8552335
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2011-12-18T14:22:02.913
FavoriteCount
0
LastActivityDate
2011-12-18T14:27:22.387
LastEditDate
2011-12-18T14:27:22.387
LastEditorUserId
376743
OwnerUserId
376743
ParentId
8552244
PostTypeId
2
Score
3
ViewCount
0
LastEditorDisplayName
text
Body
A callback is just a word to describe a function that we pass to some other code for that other code to invoke. In your example, <code>onRequest</code> is a callback function that gets passed to <code>createServer</code> to be invoked whenever a request is received. I think the issue you're having is that you're expecting <code>expand()</code> to have access to all the same variables/parameters that the <code>onRequest</code> function has access to. This isn't the case. You need pass the <code>response</code> object to <code>expand()</code>. Because the call to <code>expand</code> creates a new callback <code>longURL</code> for the <code>http.get</code> call, it will have access to the <code>response</code> object that you passed in. <pre><code>function expand( resp ) { // receive the original response object, and end the response when ready var short = url.parse('http://t.co/wbDrgquZ'); var options = { host: short.hostname, port: 80, path: short.pathname }; function longURL( response ) { console.log(response.headers.location); resp.end( response.headers.location ); // end the original response } http.get(options, longURL); } function start() { function onRequest(request, response) { console.log("Request received."); response.writeHead(200, { "Content-Type": "text/plain" }); response.write("Hello World"); expand( response ); // pass this response object to expand } http.createServer(onRequest).listen(8888); console.log("Server has started."); } </code></pre>
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POUnderstanding callbacks in Javascript and node.js
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USRightSaidFred
UserOwnerUserId
1. USRightSaidFred
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.