Load third party JS using async

[thabti]

I ran webpagetest[1] against the website and we have some things to improve around time to first byte.

<script src="https://cdn.ravenjs.com/3.0.4/raven.min.js" async ></script>

1.https://www.webpagetest.org/result/160811_AY_9BP/

[ahmedre]

for raven specifically, this looks like it may be tricky, since setting it to async means we don't get errors during loading.

see this for more details: getsentry/sentry-javascript#169

[thabti]

Yeah kinda felt that would be an issue, especially Google Analytics and Mixpanel.

Maybe we can bundle raven/mixpanel as part of our javascript, if anything to save on http calls.

@mmahalwy thoughts on bundling raven.

[mmahalwy]

I am not sure if webpack has the ability to download/bundle unless we download them. I think we could load raven in sync but don't need mixpanel to be.

[mmahalwy]

Okay seems that mixpanel and zendesk load their script via async. All that script we have is doing is adding their code.

[thabti]

@mmahalwy They're being downloaded before DOM is ready?

We can download the files locally and bundle them as part of our script.

[mmahalwy]

no no i mean it's a script from them that embeds their script async