Server-sent events

Method of continuously sending data from a server to the browser, rather than repeatedly requesting it (EventSource interface, used to fall under HTML5)

Spec	https://html.spec.whatwg.org/multipage/comms.html#server-sent-events
Status	WHATWG Living Standard

IE	Edge	Firefox	Chrome	Safari	Opera
			103
		100	102
		99	101	TP
11	99	98	100	15.4	83
10	98	97	99	15.2-15.3	82
9	97	96	98	15.1	81
8	96	95	97	15	80
Show all
7	95	94	96	14.1	79
6	94	93	95	14	78
5.5	93	92	94	13.1	77
	92	91	93	13	76
	91	90	92	12.1	75
	90	89	91	12	74
	89	88	90	11.1	73
	88	87	89	11	72
	87	86	88	10.1	71
	86	85	87	10	70
	85	84	86	9.1	69
	84	83	85	9	68
	83	82	84	8	67
	81	81	83	7.1	66
	80	80	81	7	65
	79	79	80	6.1	64
	18	78	79	6	63
	17	77	78	5.1	62
	16	76	77	5	60
	15	75	76	4	58
	14	74	75	3.2	57
	13	73	74	3.1	56
	12	72	73		55
		71	72		54
		70	71		53
		69	70		52
		68	69		51
		67	68		50
		66	67		49
		65	66		48
		64	65		47
		63	64		46
		62	63		45
		61	62		44
		60	61		43
		59	60		42
		58	59		41
		57	58		40
		56	57		39
		55	56		38
		54	55		37
		53	54		36
		52	53		35
		51	52		34
		50	51		33
		49	50		32
		48	49		31
		47	48		30
		46	47		29
		45	46		28
		44	45		27
		43	44		26
		42	43		25
		41	42		24
		40	41		23
		39	40		22
		38	39		21
		37	38		20
		36	37		19
		35	36		18
		34	35		17
		33	34		16
		32	33		15
		31	32		12.1
		30	31		12
		29	30		11.6
		28	29		11.5
		27	28		11.1
		26	27		11
		25	26		10.6
		24	25		10.5
		23	24		10.0-10.1
		22	23		9.5-9.6
		21	22		9
		20	21
		19	20
		18	19
		17	18
		16	17
		15	16
		14	15
		13	14
		12	13
		11	12
		10	11
		9	10
		8	9
		7	8
		6	7
		5	6
		4	5
		3.6	4
		3.5
		3
		2

Safari on iOS	Opera Mini	Android Browser	Blackberry Browser	Opera Mobile	Android Chrome	Android Firefox	IE Mobile	Android UC Browser	Samsung Internet	QQ Browser	Baidu Browser	KaiOS Browser
15.4	all	99	10	64	100	98	11	12.12	16.0	10.4	7.12	2.5
15.2-15.3		4.4.3-4.4.4	7	12.1			10		15.0
15.0-15.1		4.4		12					14.0
14.5-14.8		4.2-4.3		11.5					13.0
Show all
14.0-14.4		4.1		11.1					12.0
13.4-13.7		4		11					11.1-11.2
13.3		3		10					10.1
13.2		2.3							9.2
13.0-13.1		2.2							8.2
12.2-12.5		2.1							7.2-7.4
12.0-12.1									6.2-6.4
11.3-11.4									5.0-5.4
11.0-11.2									4
10.3
10.0-10.2
9.3
9.0-9.2
8.1-8.4
8
7.0-7.1
6.0-6.1
5.0-5.1
4.2-4.3
4.0-4.1
3.2

Notes

Bugs

• Reportedly, CORS in EventSource is currently supported in Firefox 10+, Opera 12+, Chrome 26+, Safari 7.0+.

• In Firefox prior to version 36 server-sent events do not reconnect automatically in case of a connection interrupt (bug)

• Firefox currently does not support EventSource in service workers

• Firefox 52 and below do not support EventSource in web/shared workers

• Antivirus software may block the event streaming data chunks.

Resources

• HTML5 Rocks tutorial
• Blog post with demo
• has.js test
• Polyfill