It is the passenger's personal responsibility to ensure that they have valid documentation which meets the requirements of the airline, immigration and other governmental authorities at every destination. Depending on where you are flying and your nationality, there might be different visa requirements. Tianxun (Skyscanner China) does not hold any details of visa requirements.
We would advise you to check with the airline or travel agent directly for more information, and if they are not able to help you, please check the official government information for the country you are visiting. You could contact the local Embassy or Consulate of the country you intend to visit prior to making a flight reservation, and they should be able to provide additional assistance.