TypeScript allows us to use type annotations to overcome the scenarios in which the type inference system is not powerful enough to automatically detect the type of a variable.
Let's consider the add function one more time:
function add(a, b) { return a + b;}
The type of the function add is inferred as the following type:
(a: any, b: any) => any;
The preceding type is a problem because the usage of the any type effectively prevents the TypeScript compiler from detecting certain errors. For example, we might expect the add function to add two numbers:
let result1 = add(2, 3); // 5
However, if we pass a string as input, we will encounter an unexpected result:
let result2 = add("2", 3); // "23"
The preceding ...
