You can try out the script and view the source code of a preliminary version on GitHub:
The app seems to be reading the elevation data correctly, but the numbers are huge ( over 20>). See the demo which shows the first 50 heights of the file. In this case, the demo shows the southern tip of Point Reyes near San Francisco CA.
The SRTM 'Quickstart Guide' says:
Heights are in meters referenced to the WGS84/EGM96 geoid