how to implement overload method in TypeScript Interface?

implementation, typescript

Solution

To implement an overloaded function, write all the overload call signatures you want to be visible first, followed by an implementation signature that is a superset of all the overload signatures. Example:

class Thing implements IThing {
    // Implement the name and age fields
    name: string;
    age: number;

    // Overload signature #1
    sayHello(name: string): string;
    // Overload signature #2
    sayHello(age: number): number;
    // Implementation signature, not visible to external callers
    sayHello(arg: any): any {
        if(typeof arg === 'string') {
            return this.name;
        } else if(typeof arg === 'number') {
            return this.age;
        } else {
            throw new Error('sayHello can only take string or a number');
        }
    }
}

var x = new Thing();
var n = x.sayHello('world'); // n: string
var a = x.sayHello(42); // a: number
var e = x.sayHello(false); // error: false is not string or number

Problem

i am new to typescript, here is a interface which i'd like to implement; ``` interface IThing{ name:string; age:number; sayHello:{ (name:string):string; (age:number):number; } } ``` sayHello has two signatures which indicates overload version. i just don't know how to implement that in a class, any help? thanks.

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