Start by adding the raven.js
script tag to your page. It should be loaded as early as possible.
<script src="https://cdn.ravenjs.com/3.26.4/raven.min.js" crossorigin="anonymous"></script>
Next configure Raven.js to use your GlitchTip DSN:
Raven.config("YOUR-GLITCHTIP-DSN-HERE").install();
At this point, Raven is ready to capture any uncaught exception.