define function typescript code example

Example 1: types function typescript

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

Example 2: typescript function

// Parameter type annotation
function greet(name: string): string {
 return name.toUpperCase();
}

console.log(greet("hello"));		// HELLO
console.log(greet(1));				// error, name is typed (string)

Example 3: typescript function type

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

Example 4: typescript function

// Named function
function add(x: number, y: number): number {
  return x + y;
}

// Anonymous function
let myAdd = function (x: number, y: number): number {
  return x + y;
};

Example 5: types function typescript

interface Easy_Fix_Solution {
    title: string;
    callback: Function;
}

Example 6: typescript annotate return type

function add(x: number, y: number): number {
  return x + y;
}