typescript define a function in a type 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 Easy_Fix_Solution {
    title: string;
    callback: Function;
}