Any

What if we declare a variable with no type annotation and no value? What does TypeScript infer as the type? Let's enter the following code in the TypeScript playground and find out:

let flag;

If we hover our mouse over flag, we see it has been given the any type:

So, the TypeScript compiler gives a variable with no type annotation and no immediately assigned value, the any type. The any type is specific to TypeScript; it doesn't exist in JavaScript. It is a way of opting out of type checking on a particular variable. It is commonly used for dynamic content or values from third-party libraries. However, TypeScript's increasingly powerful type system means that we need to use any less often these days.