events.ts

export class Event {
    public target: any;
    public type: string;
    constructor(type: string, target: any) {
        this.target = target;
        this.type = type;
    }
}

export class ErrorEvent extends Event {
    public message: string;
    public error: Error;
    constructor(error: Error, target: any) {
        super('error', target);
        this.message = error.message;
        this.error = error;
    }
}

export class CloseEvent extends Event {
    public code: number;
    public reason: string;
    public wasClean = true;
    constructor(code: number = 1000, reason: string = '', target: any) {
        super('close', target);
        this.code = code;
        this.reason = reason;
    }
}
export interface WebSocketEventMap {
    close: CloseEvent;
    error: ErrorEvent;
    message: MessageEvent;
    open: Event;
}

export interface WebSocketEventListenerMap {
    close: (event: CloseEvent) => void | {handleEvent: (event: CloseEvent) => void};
    error: (event: ErrorEvent) => void | {handleEvent: (event: ErrorEvent) => void};
    message: (event: MessageEvent) => void | {handleEvent: (event: MessageEvent) => void};
    open: (event: Event) => void | {handleEvent: (event: Event) => void};
}