How do you define and call a function in TypeScript?

In TypeScript, you can define a function using the ‘function‘ keyword followed by the function name, parameters in parentheses, and a return type after a colon. The function body is enclosed in curly braces ‘‘.

Here’s an example of a function definition in TypeScript:

function add(a: number, b: number): number {
  return a + b;
}

In this example, we’ve defined a function called ‘add‘ which takes two parameters ‘a‘ and ‘b‘ of type ‘number‘ and returns a value of type ‘number‘.

To call a function in TypeScript, you use the function name followed by the arguments within parentheses. Here’s how you can call the ‘add‘ function:

const result = add(3, 4);
console.log(result); // Output: 7

This function call passes ‘3‘ and ‘4‘ as arguments to the ‘add‘ function and stores the return value in the ‘result‘ variable.

Here’s a complete example in TypeScript:

function add(a: number, b: number): number {
  return a + b;
}

const result = add(3, 4);
console.log(result); // Output: 7

The function definition and call is represented as follows:

Function Definition:
$$\text{function add}(a: \mathbb{N}, b: \mathbb{N}): \mathbb{N} \\ \{ \\ \quad \text{return } a + b; \\ \}$$

Function Call:
const result = add(3, 4);