Lookbehind in JS regular expressions

The positive lookbehind ((?<= )) and negative lookbehind ((?<! )) zero-width assertions in JavaScript regular expressions can be used to ensure a pattern is preceded by another pattern.

Spec	https://tc39.es/ecma262/#sec-assertion
Status	Other

IE	Edge	Firefox	Chrome	Safari	Opera
			108
		107	107	TP
		106	106	16.1
11	105	105	105	16.0	91
10	104	104	104	15.6	90
9	103	103	103	15.5	89
8	102	102	102	15.4	88
Show all
7	101	101	101	15.2-15.3	87
6	100	100	100	15.1	86
5.5	99	99	99	15	85
	98	98	98	14.1	84
	97	97	97	14	83
	96	96	96	13.1	82
	95	95	95	13	81
	94	94	94	12.1	80
	93	93	93	12	79
	92	92	92	11.1	78
	91	91	91	11	77
	90	90	90	10.1	76
	89	89	89	10	75
	88	88	88	9.1	74
	87	87	87	9	73
	86	86	86	8	72
	85	85	85	7.1	71
	84	84	84	7	70
	83	83	83	6.1	69
	81	82	81	6	68
	80	81	80	5.1	67
	79	80	79	5	66
	18	79	78	4	65
	17	78	77	3.2	64
	16	77	76	3.1	63
	15	76	75		62
	14	75	74		60
	13	74	73		58
	12	73	72		57
		72	71		56
		71	70		55
		70	69		54
		69	68		53
		68	67		52
		67	66		51
		66	65		50
		65	64		49
		64	63		48
		63	62		47
		62	61		46
		61	60		45
		60	59		44
		59	58		43
		58	57		42
		57	56		41
		56	55		40
		55	54		39
		54	53		38
		53	52		37
		52	51		36
		51	50		35
		50	49		34
		49	48		33
		48	47		32
		47	46		31
		46	45		30
		45	44		29
		44	43		28
		43	42		27
		42	41		26
		41	40		25
		40	39		24
		39	38		23
		38	37		22
		37	36		21
		36	35		20
		35	34		19
		34	33		18
		33	32		17
		32	31		16
		31	30		15
		30	29		12.1
		29	28		12
		28	27		11.6
		27	26		11.5
		26	25		11.1
		25	24		11
		24	23		10.6
		23	22		10.5
		22	21		10.0-10.1
		21	20		9.5-9.6
		20	19		9
		19	18
		18	17
		17	16
		16	15
		15	14
		14	13
		13	12
		12	11
		11	10
		10	9
		9	8
		8	7
		7	6
		6	5
		5	4
		4
		3.6
		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
16.1
16.0	all	105	10	64	105	104	11	13.4	18.0	13.1	13.18	2.5
15.6		4.4.3-4.4.4	7	12.1			10		17.0
15.5		4.4		12					16.0
15.4		4.2-4.3		11.5					15.0
Show all
15.2-15.3		4.1		11.1					14.0
15.0-15.1		4		11					13.0
14.5-14.8		3		10					12.0
14.0-14.4		2.3							11.1-11.2
13.4-13.7		2.2							10.1
13.3		2.1							9.2
13.2									8.2
13.0-13.1									7.2-7.4
12.2-12.5									6.2-6.4
12.0-12.1									5.0-5.4
11.3-11.4									4
11.0-11.2
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

Resources

• Blog post on lookbehind assertions
• Firefox implementation bug
• MDN: Regular Expressions Assertions
• Safari implementation bug