write a function in typescript code example

Example 1: typescript default parameter

// Default Parameters
sayHello(hello: string = 'hello') { 
    console.log(hello); 
}

sayHello(); // Prints 'hello'

sayHello('world'); // Prints 'world'

Example 2: types function typescript

interface Safer_Easy_Fix {
    title: string;
    callback: () => void;
}
interface Alternate_Syntax_4_Safer_Easy_Fix {
    title: string;
    callback(): void;
}

Example 3: typescript default parameter

function sayName({ first, last = 'Smith' }: {first: string; last?: string }): void {
  const name = first + ' ' + last;
  console.log(name);
}

sayName({ first: 'Bob' });

Example 4: typescript function type

// define your parameter's type inside the parenthesis
// define your return type after the parenthesis

function sayHello(name: string): string  {
  console.log(`Hello, ${name}`!);
}

sayHello('Bob'); // Hello, Bob!

Example 5: typescript function type

interface Date {
  toString(): string;
  setTime(time: number): number;
  // ...
}

Example 6: simple function in typescript

// Named function

//function with type as number
function add(x: number, y: number): number {
  // return sum of numbers entered as params
  return x + y;
}

// Anonymous function

// variable to call and define function
let myAdd = function (x: number, y: number): number {
  // return sum of numbers entered as params
  return x + y;
};