Check if function name exists in function map?

I just spent a lot of time debugging an issue, and it turns out I had one letter off in the function name string when calling a function from a function map (I used "playball" instead of "playBall").

Is there a way to check if a function exists in a function map?

I don't use function maps because they are PITA to deal with. If I need to call functions by name I use scripting:

try { 
 runtime.callFunction(localVars.functionName) 
}
catch(e) { 	
 // console.log("function does not exist");
}