typescript function type 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 as parameter
function createPerson(name: string, doAction: () => void): void {
console.log(`Hi, my name is ${name}.`);
doAction(); // doAction as a function parameter.
}
// Hi, my name is Bob.
// performs doAction which is waveHands function.
createPerson('Bob', waveHands());
Example 4: typescript function type
interface getUploadHandlerParams {
checker : Function
}
Example 5: 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 6: typescript function type
interface Date {
toString(): string;
setTime(time: number): number;
// ...
}