typescript函数重载

ts-overload.ts

export class TestClass {
    someMethod(): number;
    someMethod(str: string): string;

    someMethod(str?: string) {
        if ( typeof str === 'string' ) {
            return str + '123';
        } else {
            return Math.random();
        }
    }
}

const testClass = new TestClass()
testClass.someMethod()