In this example I used ow for runtime arguments type checking, but you can check yourself typeof a === 'string'
import ow from "ow";
function myMethod(a: string): string;
function myMethod(a: number): number;
function myMethod(a: number, b: string): [number, string];
function myMethod(
a: string | number,
b?: string
): string | number | [number, string] {
if (ow.isValid(a, ow.string) && ow.isValid(b, ow.undefined)) {
console.log("function myMethod(a: string): string");
return a;
}
if (ow.isValid(a, ow.number) && ow.isValid(b, ow.undefined)) {
console.log("function myMethod(a: number): number");
return a;
}
if (ow.isValid(a, ow.number) && ow.isValid(b, ow.string)) {
console.log("function myMethod(a: number, b: string): [number, string]");
return [a as number, b];
}
}
console.log(myMethod(123));
// function myMethod(a: number): number
// 123
console.log(myMethod("Andrew"));
// function myMethod(a: string): string
// Andrew
console.log(myMethod(123, "Andrew"));
// function myMethod(a: number, b: string): [number, string]
// [123, "Andrew"]
Same is valid for classes
import ow from "ow";
class MyClass {
myMethod(a: string): string;
myMethod(a: number): number;
myMethod(a: number, b: string): [number, string];
myMethod(
a: string | number,
b?: string
): string | number | [number, string] {
if (ow.isValid(a, ow.string) && ow.isValid(b, ow.undefined)) {
console.log("function myMethod(a: string): string");
return a;
}
if (ow.isValid(a, ow.number) && ow.isValid(b, ow.undefined)) {
console.log("function myMethod(a: number): number");
return a;
}
if (ow.isValid(a, ow.number) && ow.isValid(b, ow.string)) {
console.log("function myMethod(a: number, b: string): [number, string]");
return [a as number, b];
}
}
}
const myClass = new MyClass()
console.log(myClass.myMethod(123));
// function myMethod(a: number): number
// 123
console.log(myClass.myMethod("Andrew"));
// function myMethod(a: string): string
// Andrew
console.log(myClass.myMethod(123, "Andrew"));
// function myMethod(a: number, b: string): [number, string]
// [123, "Andrew"]
Top comments (1)
Nice - I didn't know about that!
I neatened up your example a little: diffchecker.com/FuL9OkcM