What is it

Function Declaration

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

Function Expression

const addNumbers = (a: number, b: number): number => a + b;

Breakdown

• (): string is a return type
  • Represents type of the value that is returned from a function
• (param: int) represents the parameters of the function, where the type is an integer
  • Parameters need their own typing

Optionals

// void return type
function messageLogger(message: string): void {
  console.log(message);
}

// primitive return type
function addNumbers(a: number, b: number): number {
  return a + b;
}

// Optional Parameter `y`
function newFunc(x: number, y?: number) {
  ...
}

// Default Parameter
function newFunc(name: string = "you"){
  ...
}