Check out example codes for "why does my if statement still run when the its not true c++". It will help you in understanding the concepts better.

Code Example 1

If the condition is true, result is set to 1, so much is true.
But in the other case, the content of result is undefined - 
so it can be anything,
even allowing the compiler to modify it at will as part of an 
optimization. 
You should either initialize result at its declaration,or add an else 
branch where you set it to the alternative value.

Learn ReactJs, React Native from akashmittal.com