How to add type of property in Typescript?-CodePudding

I have this code

type WithRequiredProperty<Type, Key extends keyof Type> = Omit<Type, Key> & {
    [Property in Key]-?: Type[Property];
};

export type MessageWithMdEnforced = WithRequiredProperty<IMessage, 'md'>;

export interface IMessage extends IClass {
    rid: RoomID;
    msg: string;
    tmid?: string;
    tshow?: boolean;
    ts: Date;
}

The problem is that IMessage is imported from node_modules so I can not change in node_modules And I want to add errorReason: string type in IMessage interface

Can Anyone tell me what to do ? How to achieve this ?

CodePudding user response：

You just need to create new interface extended by IMessage so that the properties will be inherited to your new interface and use the new interface

type WithRequiredProperty<Type, Key extends keyof Type> = Omit<Type, Key> & {
    [Property in Key]-?: Type[Property];
};

interface NewMessage extends IMessage {
    errorReason?: string;
} 

export type MessageWithMdEnforced = WithRequiredProperty<NewMessage, 'md'>;