I'm trying to place a JavaScript code to my WordPress post but nothing displayed:

I'm using the custom fields method using the Code Embed plugin.

The JavaScript is taken from this link and here's the full code:

<script type="text/javascript">function ch_st_loaded(speedtest) {speedtest.start();}</script><script async type="text/javascript" src="//cloudharmony.com/rum/speedtest-google:compute-asia-east1.js"></script>

Am I implementing this correctly? Appreciate if someone can correct me or provide alternative. Thanks!