Add explicit support for null url

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-use-websocket",
-  "version": "1.7.2",
+  "version": "1.7.3",
   "description": "React Hook for WebSocket communication",
   "main": "./dist/index.js",
   "files": [

src/lib/constants.ts

@@ -10,6 +10,7 @@ export const DEFAULT_RECONNECT_LIMIT = 20;
 export const DEFAULT_RECONNECT_INTERVAL_MS = 5000;
 
 export enum ReadyState {
+  UNINSTANTIATED = -1,
   CONNECTING = 0,
   OPEN = 1,
   CLOSING = 2,

src/lib/use-socket-io.ts

@@ -37,7 +37,7 @@ const getSocketData = (event: WebSocketEventMap['message']): SocketIOMessageData
 }
 
 export const useSocketIO = (
-  url: string | (() => string | Promise<string>),
+  url: string | (() => string | Promise<string>) | null,
   options: Options = DEFAULT_OPTIONS,
 ): [SendMessage, SocketIOMessageData, ReadyState, () => WebSocket] => {
   const optionsWithSocketIO = useMemo(() => ({

src/lib/use-websocket.ts

@@ -12,7 +12,7 @@ import {
 } from './types';
 
 export const useWebSocket = (
-  url: string | (() => string | Promise<string>),
+  url: string | (() => string | Promise<string>) | null,
   options: Options = DEFAULT_OPTIONS,
 ): [SendMessage, WebSocketEventMap['message'], ReadyState, () => WebSocket] => {
   const [ lastMessage, setLastMessage ] = useState<WebSocketEventMap['message']>(null);
@@ -29,7 +29,9 @@ export const useWebSocket = (
   const readyStateFromUrl =
     convertedUrl.current && readyState[convertedUrl.current] !== undefined ?
       readyState[convertedUrl.current] :
-      ReadyState.CONNECTING;
+      url !== null ?
+        ReadyState.CONNECTING :
+        ReadyState.UNINSTANTIATED;
 
   const sendMessage: SendMessage = useCallback(message => {
     if (webSocketRef.current && webSocketRef.current.readyState === ReadyState.OPEN) {