TypeScript: How to add static methods to built-in classes

Question

Is there anyhow anyway to add some static method to types like Date, String, Array, etc?

For example I want to add method to

Answer 1

You have to augment the DateConstructor interface to add static properties:

declare global {
    interface DateConstructor {
        today: () => Date
    }
}   

Date.today = function(){
    let date = new Date;
    date.setHours(0,0,0,0);
    return date;
}

Similarly extend StringConstructor and ArrayConstructor for string and arrays. See declaration merging.