Javascript functions var global

Question

And I can't figure out how to make

spotify.search({ type: 'track', query: 'dancing in the moonlight' }, function(err, data){
   return data; 
});

data globaly available?

i tried like butin var data = in front of that but it didn't help

You should have a look at http://stackoverflow.com/q/14220321/218196 to understand how asynchronous code works. While you can make the value global, you have to pay attention to *when* you are accessing it. As demonstrated in the answer, passing the response to a callback is a better approach. Or use promises, there are Node libraries for them as well. — Felix Kling, May 17 '13 at 16:52

score 2 · Accepted Answer · answered May 17 '13 at 16:51

2

If you need that data to be available "globally" in the current file scope, just define another var outside that call:

var myData;
spotify.search({ type: 'track', query: 'dancing in the moonlight' }, function(err, data){
  myData = data;
});

If you need it to be available globally across your Node process, then do the following:

spotify.search({ type: 'track', query: 'dancing in the moonlight' }, function(err, data){
  global.myData = data;
});

answered May 17 '13 at 16:51

gustavohenke

Thank you, I used the global one. – Jonhhan May 17 '13 at 16:55
2

FYI: Using `global` works, but is considered bad coding style. – TheHippo May 17 '13 at 17:00
1

That solves the problem of *where* you can read the variable, but it doesn't help with the problem of *when* you can read it. That's the entire reason for using callbacks in the first place. The next question will be "Why does `myData` have an `undefined` value even though I set it in the callback?" :-) (Answer: the callback hasn't run yet.) Of course if the rest of the code takes this into account it will be OK, but still how do you know when `myData` becomes available? That's why the usual way is to take some action directly in the callback or in a function it calls. – Michael Geary May 17 '13 at 17:08

1 Answers1