TypeScript中的嵌套类抛出错误

Question

I was following instructions in the official TypeScript handbook under the section "Merging Namespaces with Classes" for how to get nested classes. But it looks like if I try to add a function declaration of any type in the child class definition I get the TS error

"An accessor cannot be declared in an ambient context"

I don't know what this means or why I'm getting this when I'm following the example exactly as far as I can tell.

export class Schedule {
    // ...
}

export declare namespace Schedule {
    export class MaxGracePeriod {
        // Static, read-only constants in TypeScript (See: https://stackoverflow.com/a/22993349/1504964)
        public static get Hourly(): number { return 12; }
        public static get Daily(): number { return 12; }
        public static get Weekly(): number { return 12; }
        public static get Monthly(): number { return 24; }
        public static get Yearly(): number { return 24; }       
        //                ~~~~~~ => "An accessor cannot be declared in an ambient context"
    }

    export enum DaysOfWeek {
        Sunday = 0,
        Monday = 1,
        Tuesday = 2,
        Wednesday = 3,
        Thursday = 4,
        Friday = 5,
        Saturday = 6,
    }
}

I get the red squiggle and error on the Hourly() , Daily() , etc. definitions.

Answer 1

Remove declare from the namespace definition. You don't need that.

export class Schedule {
    // ...
}

export namespace Schedule {
    export class MaxGracePeriod {
        public static get Hourly(): number { return 12; }
        public static get Daily(): number { return 12; }
        public static get Weekly(): number { return 12; }
        public static get Monthly(): number { return 24; }
        public static get Yearly(): number { return 24; }       
    }

    export enum DaysOfWeek {
        Sunday = 0,
        Monday = 1,
        Tuesday = 2,
        Wednesday = 3,
        Thursday = 4,
        Friday = 5,
        Saturday = 6,
    }
}