title: how to implement video viewability like google
body: <p>I wanted to do something like <a href="https://viewability.withgoogle.com/static/video.html" rel="nofollow noreferrer">google viewability</a>.
  Till now, I created a js to check element is in viewport or not. but I am not able to found a way to load my js on ssp side. and the only data we are sending to ssp is one xml file (vast standard). there is no way to load js through xml on ssp.</p>
  
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  I don't know what information should I provide. Anything would be helpful I just need a direction to start my work, thanks in advance.
  </p>