Functions and Return Types

Functions become much safer with types.

Typed parameters and return

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

Void return

function log(msg: string): void {
  console.log(msg);
}

Optional parameters

function greet(name: string, title?: string): string {
  return title ? `${title} ${name}` : name;
}

Default values

function power(base: number, exp: number = 2): number {
  return base ** exp;
}

Arrow functions

const multiply = (a: number, b: number): number => a * b;

Remember

• always type inputs
• specify return when possible
• optional params use ?