by Casey Ng
Message is optional. Just type the phone number and click send.
Works with both WhatsApp and WhatsApp business.
V2: Updated for error handling.
V3: fixed an error where multiple sim cards are in the phone.
V4: modified it so that the flow will use the sim card that is first detected instead of hard coding to the first slot. I.e. the flow now checks for sim#1 followed by sim#2.
V5: changed the way messages are sent to increase robustness.
V6: allow parallel launches.
V7,8,9,10,11,12: increase robustness.
V13: changed variable names.
V14: applied css to align the form vertically.