CODEWITHSUNDEEP
javascriptfacebook
frenchie
frenchie

Reputation: 51937

Loading Facebook pixel async

I'm loading the Facebook pixel and getting an error because the script isn't loaded when the call is made. This is what it looks like:

function Load3rdPartyScripts() {

    (function (f, b, e, v, n, t, s) {
        if (f.fbq) return; n = f.fbq = function () {
            n.callMethod ?
            n.callMethod.apply(n, arguments) : n.queue.push(arguments)
        }; if (!f._fbq) f._fbq = n;
        n.push = n; n.loaded = !0; n.version = '2.0'; n.queue = []; t = b.createElement(e); t.async = !0;
        t.src = v; s = b.getElementsByTagName(e)[0]; s.parentNode.insertBefore(t, s)
    })(window, document, 'script', 'https://connect.facebook.net/en_US/fbevents.js', undefined, undefined, undefined);

    fbq('init', 'XXXXXXXXXXXXX'); //problem here
    fbq('track', 'PageView');

}

Problem is that fbq isn't initiated when the code runs. Now I know I could wrap the problem code inside a setInterval and keep checking until the external script is fully loaded but I'm wondering if there's a better way to do it.

Upvotes: 1

Views: 7548

Answers (1)

Mouneer
Mouneer

Reputation: 13489

I tried to reproduce this problem but in vain. Your code works perfectly. fbq is appended syncronously (So no need to timeout) to window and will be called normally. Check yourself:

(function Load3rdPartyScripts() {

    (function (f, b, e, v, n, t, s) {
        if (f.fbq) return; n = f.fbq = function () {
            n.callMethod ?
            n.callMethod.apply(n, arguments) : n.queue.push(arguments)
        }; if (!f._fbq) f._fbq = n;
        n.push = n; n.loaded = !0; n.version = '2.0'; n.queue = []; t = b.createElement(e); t.async = !0;
        t.src = v; s = b.getElementsByTagName(e)[0]; s.parentNode.insertBefore(t, s)
    })(window, document, 'script', 'https://connect.facebook.net/en_US/fbevents.js', undefined, undefined, undefined);

    fbq('init', 'XXXXXXXXXXXXX'); // No problem here!
    fbq('track', 'PageView');

})();

But

There are some potential reasons that may produce your error:

  1. Running the script outside the browser, An env that ruined the window variable.

  2. Running code on browser but with a freezed window (Object.freeze(window)) causes that fbq will be undefined

  3. So also Object.seal(window) like freeze(). It will prevent new properties from being added to window

  4. Creating a local scope named window variable will cause fbq to be undefined

    function Load3rdPartyScripts() {
    let window = {};  // Notice!
    (function (f, b, e, v, n, t, s) {
        if (f.fbq) return; n = f.fbq = function () {
            n.callMethod ?
            n.callMethod.apply(n, arguments) : n.queue.push(arguments)
        }; if (!f._fbq) f._fbq = n;
        n.push = n; n.loaded = !0; n.version = '2.0'; n.queue = []; t = b.createElement(e); t.async = !0;
        t.src = v; s = b.getElementsByTagName(e)[0]; s.parentNode.insertBefore(t, s)
    })(window, document, 'script', 'https://connect.facebook.net/en_US/fbevents.js', undefined, undefined, undefined);

    fbq('init', 'XXXXXXXXXXXXX'); //problem here
    fbq('track', 'PageView');

}
Load3rdPartyScripts();

Upvotes: 4

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