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Editorial Team
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Asked: 2026-05-27T19:57:33+00:00

I have an issue. One of my JS scripts needs Facebook SDK and Twitter

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I have an issue. One of my JS scripts needs Facebook SDK and Twitter widgets JS to load first. Facebook creates FB object, Twitter creates twttr object. Both of them create these objects AFTER my script fires, even though they’re loaded from <head>.

I think solution is to periodically check if FB and twttr are defined, and then proceed with executing my script. But I have no idea how to do this.

I tried creating a loop 

while (typeof FB === 'undefined' || typeof twttr === 'undefined' || typeof twttr.widgets === 'undefined') {
    // run timeout for 100 ms with noop inside
}

But this clearly does not work as it keeps firing timeouts at a high speed and page hangs.

Please help me, I can’t sleep because of this issue.

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1 Answer

  1. Editorial Team

    If the scripts are loaded in the normal, synchronous way, then just make sure that your <script> include appears after the library scripts in the document’s <head>. If, on the other hand, those scripts are loading objects asynchronously (as seems to be the case), then create something like this:

    function whenAvailable(name, callback) {
    var interval = 10; // ms
    window.setTimeout(function() {
        if (window[name]) {
            callback(window[name]);
        } else {
            whenAvailable(name, callback);
        }
    }, interval);
}

    And use it like this:

    whenAvailable("twttr", function(t) {
    // do something
});

    The function given in the second argument to whenAvailable will not execute until twttr is defined on the global window object. You can do the same thing for FB.

    Important note: Those libraries probably also provide some built-in way to execute code after they have loaded. You should look for such hooks in their respective documentation.

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