Necessary components of the tag for it to load correctly:
id="str-in-prog" this is what the Sharethrough Technology looks for when trying to identify which placement’s mediation network loaded the script.
The script itself has two parts: one for loading passback when directly on the page, and another for loading passback within an iframe. We recommend keeping the entire script as it is to preserve the reliability of passing impressions.
How Passback Works
Passback should be loaded as backfill for mediation networks that cannot fill an impression. This is necessary for unfilled impressions to be passed down the waterfall. When the passback script is loaded, it looks up at its parents in the page to determine which instance of data-str-mediation-key doesn't have fill. If not placed within a Sharethrough data-str-mediation-key tag, it will not be able to determine which Sharethrough placement needs an ad.
Testing with Preview URLs
If passback is loaded when using a preview URL, the tech will not load the next network in the waterfall. Instead, to verify passback was loaded, the id will change from str-in-prog to str-done.