typescript interface optional function code example

Example 1: typescript optional parameters

// Optional Parameters
sayHello(hello?: string) {
	console.log(hello);
}

sayHello(); // Prints 'undefined'

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

Example 2: ts interface optional parameter

interface Person {
    name: string;
    age: number;
    phone?: string;
}

let p: Person = {name: "Ashlee", age: 29};
console.log(p);

Example 3: typescript optional parameters

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

sayHello(); // Prints 'hello'

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