I am Dominican citizen, I am travelling to Botswana from DOH-JNB-GBE. Do I need a transit visa in JNB (O. R. Tambo International Airport, South Africa)?
According to the website of the South African Consulate in the US, Transit Visa - 3 Days or less you do not need a transit visa. From that link:
Travelers transiting through the following international airports are exempted from/do not have to be in possession of transit visas, but will be subjected to biometric capturing directly at the airport:
OR Tambo International;
Cape Town International;
Please note that the above-mentioned exemption does not apply to deportees. Please also note that foreigners who are utilizing land ports of entry to transit through the Republic of South Africa and who are subject to South Africa visa control should apply for and be issued with port of entry visas.
So if you were using a land port of entry you would need a transit visa