KY039 Arduino Heart rate code

Using Arduino Programming Questions
3

Hi,
I tried to delete spacing , sorry.
with commas is the same, with using commas,I tried to get value, oldvalue and change still weird too.
I add a pic of the sensor

Promotion-5pcs-lot-5V-Heartbeat-Sensor-Senser-Detector-Module-By-Finger-For-Arduino.jpg_50x50.jpg