-
Notifications
You must be signed in to change notification settings - Fork 5
/
eventsource.ts
309 lines (269 loc) · 9.38 KB
/
eventsource.ts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
import { ConsoleLogger, Logger } from './logger';
import { EventSourceMessage, getLines, getMessages, readChunks } from './parse';
const ContentTypeEventStream = 'text/event-stream';
export type EventSourceOptions = {
/**
* Disables connection retrying.
*/
disableRetry?: boolean;
/**
* Delay in milliseconds for retrying connection.
*/
retry?: number;
/**
* Disables logging.
*/
disableLogger?: boolean;
/**
* Logger to use for events and errors. Defaults to console.
*/
logger?: Logger;
/**
* Fetch implementation to use for connecting. Defaults to {@link globalThis.fetch}
*/
fetch?: typeof fetch;
} & Omit<RequestInit, 'cache' | 'credentials' | 'signal'>;
/**
* @deprecated
*/
export type EventSourceExtraOptions = {
/**
* @deprecated Use {@link EventSourceOptions#fetch} instead
*/
fetchInput?: typeof fetch;
};
export class CustomEventSource extends EventTarget implements EventSource {
// https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource-url
public url: string;
// https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource-readystate
public readonly CONNECTING = 0;
public readonly OPEN = 1;
public readonly CLOSED = 2;
public readyState = this.CONNECTING;
// https://html.spec.whatwg.org/multipage/server-sent-events.html#handler-eventsource-onopen
public onerror: ((this: EventSource, ev: Event) => any) | null = null;
// https://html.spec.whatwg.org/multipage/server-sent-events.html#handler-eventsource-onmessage
public onmessage: ((this: EventSource, ev: MessageEvent) => any) | null =
null;
// https://html.spec.whatwg.org/multipage/server-sent-events.html#handler-eventsource-onerror
public onopen: ((this: EventSource, ev: Event) => any) | null = null;
public onRetryDelayReceived:
| ((this: EventSource, delay: number) => any)
| null = null;
public readonly options: EventSourceInit & EventSourceOptions;
private readonly extraOptions?: EventSourceExtraOptions;
private abortController?: AbortController;
private timeoutId: ReturnType<typeof setTimeout> | undefined = undefined;
private retry: number;
private currentLastEventId?: string;
private logger?: Logger;
constructor(
url: string | URL,
initDict?: EventSourceInit & EventSourceOptions,
/**
* @deprecated Use the related options in initDict
*/
extraOptions?: EventSourceExtraOptions,
) {
super();
this.options = initDict ?? {};
this.extraOptions = extraOptions;
this.url = url instanceof URL ? url.toString() : url;
this.retry = initDict?.retry ?? 5000;
if (!this.options.disableLogger) {
this.logger = this.options.logger ?? new ConsoleLogger();
}
this.connect();
}
// https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource-withcredentials
public get withCredentials(): boolean {
return this.options.withCredentials ?? false;
}
public get retryDelay(): number {
return this.retry;
}
private async connect(lastEventId?: string) {
if (this.readyState === this.CLOSED) {
this.logger?.warn(
'Canceled reconnecting due to state already being closed',
);
return;
}
try {
// https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource
this.abortController = new AbortController();
this.readyState = this.CONNECTING;
const fetchOptions: RequestInit = {
...this.options,
headers: lastEventId
? {
...this.options.headers,
Accept: ContentTypeEventStream,
'Last-Event-ID': lastEventId,
}
: {
...this.options.headers,
Accept: ContentTypeEventStream,
},
cache: 'no-store',
credentials: this.withCredentials ? 'include' : 'omit',
signal: this.abortController?.signal,
};
const response = this.options.fetch
? await this.options.fetch(this.url, fetchOptions)
: this.extraOptions?.fetchInput
? await this.extraOptions.fetchInput(this.url, fetchOptions)
: await globalThis.fetch(this.url, fetchOptions);
// https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource (Step 15)
if (response.status !== 200) {
return this.failConnection(
`Request failed with status code ${response.status}`,
);
} else if (
!response.headers.get('Content-Type')?.includes(ContentTypeEventStream)
) {
return this.failConnection(
`Request failed with wrong content type '${response.headers.get(
'Content-Type',
)}'`,
);
} else if (!response?.body) {
return this.failConnection(`Request failed with empty response body'`);
}
this.announceConnection();
const reader: ReadableStreamDefaultReader<Uint8Array> =
response.body.getReader();
const getLine = getLines();
const getMessage = getMessages();
for await (const chunk of readChunks(reader)) {
for await (const [line, fieldLength] of getLine(chunk)) {
for await (const [message, id, retry] of getMessage(
line,
fieldLength,
)) {
if (typeof id !== 'undefined') {
this.currentLastEventId = id;
} else if (typeof retry !== 'undefined') {
this.retry = retry;
this.onRetryDelayReceived?.(retry);
} else if (message) {
this.dispatchMessage(
message,
this.currentLastEventId,
response.url,
);
}
}
}
}
} catch (error: any) {
if (typeof error === 'object' && error?.name === 'AbortError') {
return;
}
await this.reconnect('Reconnecting EventSource because of error', error);
return;
}
await this.reconnect('Reconnecting because EventSource connection closed');
}
// https://html.spec.whatwg.org/multipage/server-sent-events.html#reestablish-the-connection
private async reconnect(msg?: string, error?: unknown) {
const event = new Event('error');
this.dispatchEvent(event);
this.onerror?.(event);
if (error) {
this.logger?.warn('Error occurred in EventSource', error ?? '');
}
if (this.readyState === this.CLOSED || this.options.disableRetry) {
return;
}
if (msg) {
this.logger?.warn(msg, error ?? '');
}
this.timeoutId = setTimeout(async () => {
await this.connect(this.currentLastEventId);
}, this.retry);
}
// https://html.spec.whatwg.org/multipage/server-sent-events.html#dispatchMessage
private dispatchMessage(
message: EventSourceMessage,
lastEventId?: string,
url?: string,
) {
const origin = url && URL.canParse(url) ? new URL(url) : undefined;
const eventType = !message?.event ? 'message' : message.event;
const event = new MessageEvent(eventType, {
data: message?.data,
// https://html.spec.whatwg.org/multipage/server-sent-events.html#dispatchMessage (Note)
lastEventId: message?.id || lastEventId,
origin: origin?.origin,
});
this.dispatchEvent(event);
if (eventType === 'message') {
this.onmessage?.(event);
}
}
// https://html.spec.whatwg.org/multipage/server-sent-events.html#fail-the-connection
private failConnection(error: unknown) {
this.logger?.error('Fatal error occurred in EventSource', error);
this.readyState = this.CLOSED;
const event = new Event('error');
this.dispatchEvent(event);
this.onerror?.(event);
}
// https://html.spec.whatwg.org/multipage/server-sent-events.html#announce-the-connection
private announceConnection() {
this.logger?.debug('Connection established');
this.readyState = this.OPEN;
const event = new Event('open');
this.dispatchEvent(event);
this.onopen?.(event);
}
// https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource-close
public close() {
this.readyState = this.CLOSED;
clearTimeout(this.timeoutId);
this.abortController?.abort();
}
override addEventListener(
type: string,
listener: (this: EventSource, event: MessageEvent) => any,
options?: boolean | AddEventListenerOptions,
): void;
override addEventListener(
type: string,
listener: EventListenerOrEventListenerObject,
options?: boolean | AddEventListenerOptions,
): void;
override addEventListener<K extends keyof EventSourceEventMap>(
type: K,
listener: (this: EventSource, ev: EventSourceEventMap[K]) => any,
options?: boolean | AddEventListenerOptions,
): void {
super.addEventListener(
type,
listener as EventListenerOrEventListenerObject,
options,
);
}
override removeEventListener(
type: string,
listener: (this: EventSource, event: MessageEvent) => any,
options?: boolean | EventListenerOptions,
): void;
override removeEventListener(
type: string,
listener: EventListenerOrEventListenerObject,
options?: boolean | EventListenerOptions,
): void;
override removeEventListener<K extends keyof EventSourceEventMap>(
type: K,
listener: (this: EventSource, ev: EventSourceEventMap[K]) => any,
options?: boolean | EventListenerOptions,
): void {
super.removeEventListener(
type,
listener as EventListenerOrEventListenerObject,
options,
);
}
}