make timeout before connection configurable (#16)

* make timeout before connection configurable

* add missing type

---------

Co-authored-by: Martynas Bardauskas <martynas.bardauskas@eneba.com>

Author: mbardauskas

README.md

@@ -187,6 +187,7 @@ new EventSource(url: string | URL, options?: EventSourceOptions);
 const options: EventSourceOptions = {
   method: 'GET'; // Request method. Default: GET
   timeout: 0; // Time after which the connection will expire without any activity: Default: 0 (no timeout)
+  timeoutBeforeConnection: 500; // Time to wait before initial connection is made: Default: 500ms
   headers: {}; // Your request headers. Default: {}
   body: undefined; // Your request body sent on connection: Default: undefined
   debug: false; // Show console.debug messages for debugging purpose. Default: false

index.d.ts

@@ -50,6 +50,7 @@ export interface EventSourceOptions {
   body?: any;
   debug?: boolean;
   pollingInterval?: number;
+  timeoutBeforeConnection?: number;
 }
 
 export type EventSourceEvent = MessageEvent | OpenEvent | CloseEvent | TimeoutEvent | ErrorEvent | ExceptionEvent;

src/EventSource.js

@@ -23,6 +23,7 @@ class EventSource {
     this.headers = options.headers || {};
     this.body = options.body || undefined;
     this.debug = options.debug || false;
+    this.timeoutBeforeConnection = options.timeoutBeforeConnection ?? 500;
 
     this._xhr = null;
     this._pollTimer = null;
@@ -37,7 +38,7 @@ class EventSource {
       this.url = url;
     }
 
-    this._pollAgain(500);
+    this._pollAgain(this.timeoutBeforeConnection);
   }
 
   _pollAgain(time) {