Variable loses its assigned value

Asked Oct 15 '15 at 13:52

Active Oct 15 '15 at 13:53

Viewed 34 times

I am experimenting with the facebook API to retrieve information about events.

I made functions to retrieve the event's name, date, location, ... But i'm struggling to return the event information from it's function correctly.

function retrieveEventName(eventID) {
    var name = "test";

    FB.api(eventID, // Make the API call
      function (response) {
        if (response && !response.error) {
          name = response.name;
          // name = correct name of the event (NOT "test" any more!)
        }
      }
    );

    // name = test   "name" lost it's event name and is "test" again, WHY?
    return name; // returns "test" instead of the event's name...
}

I must be missing something elementary about javascript, but I was not able to find what is causing this problem (I presume a problem with scopes (caused by the nested function in the API call) but could not find any information about JS scopes that would explain the problem).

Note that i am sure that name is the name of the event when i'm in the if clause (I printed it to test it).

edited Oct 15 '15 at 13:53

JAAulde

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asked Oct 15 '15 at 13:52

Kevin

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Yes, you are missing something elementary, *asynchronity*... – meskobalazs Oct 15 '15 at 13:53
The Facebook API call is **asynchronous**. The callback is invoked when the operation completes, but the API call itself returns immediately. You can't use a `return` like that to get the value back. – Pointy Oct 15 '15 at 13:53
So we're saying it's asynchronous? – Dave Newton Oct 15 '15 at 13:54
Oh dear! Thanks guys, that indeed explains this behaviour :) – Kevin Oct 15 '15 at 13:55
it's asynchronous... sorry had to say it :D – taxicala Oct 15 '15 at 13:55
1

Man these comments were sure not synchronous. – epascarello Oct 15 '15 at 13:55

Variable loses its assigned value

0 Answers0