code: function makePrefixMap(styleProp, eventName) {
    const prefixes = {};
  
    prefixes[styleProp.toLowerCase()] = eventName.toLowerCase();
    prefixes[`Webkit${styleProp}`] = `webkit${eventName}`;
    prefixes[`Moz${styleProp}`] = `moz${eventName}`;
    prefixes[`ms${styleProp}`] = `MS${eventName}`;
    prefixes[`O${styleProp}`] = `o${eventName.toLowerCase()}`;
  
    return prefixes;
  }
docs: ================= Transition ================= Event wrapper. Copy from react source code