This is especially useful if you are using TypeScript (or Flow I assume) because the type checker can give you an error at compile time. After performing the ru

This is especially useful if you are using TypeScript (or Flow I assume) because the type checker can give you an error at compile time. After performing the runtime check, TypeScript will know that null/undefined is not possible. See this example https://goo.gl/AyoC3T https://goo.gl/AyoC3T