typescript function parameter type code example
Example 1: typescript default parameter
sayHello(hello: string = 'hello') {
console.log(hello);
}
sayHello();
sayHello('world');
Example 2: typescript parameter function type
class Foo {
save(callback: (n: number) => any) : void {
callback(42);
}
}
var foo = new Foo();
var strCallback = (result: string) : void => {
alert(result);
}
var numCallback = (result: number) : void => {
alert(result.toString());
}
foo.save(strCallback);
foo.save(numCallback);
Example 3: typescript function as parameter
function createPerson(name: string, doAction: () => void): void {
console.log(`Hi, my name is ${name}.`);
doAction();
}
createPerson('Bob', waveHands());
Example 4: typescript set argument type
function add(x, y) {
return x + y;
}
function add(x: number, y: number): number {
return x + y;
}