JavaScript to obtain the keyboard action value (the key value of the keyboard)

Javascript contains three event handles in the input states of the corresponding keyboard: keydown, keypress, and keyup.

The corresponding meaning is: the button is pressed (the button is pressed but not yet lifted), click the button (Press and raise the button), the button is lifted (after the button is lifted)

Key Category
Buttons can be divided into "real key" and "virtual key"
The real key can be understood as the buttons that we can see and print, such as the letter "A", number "1", and character "?" And so on.
Virtual keys are keys that cannot be printed out for control, such as Ctrl, ALT, shift, and arrow keys.
IE has a special case when processing the virtual key: the virtual key does not generate a keypress event and must be captured using keydown or keyup.

Key code and Verification Code
The key code is used by a computer to identify the encoding of different keys. Each key has a key code.
The escape code is unique to printable keys and corresponds to the characters displayed on the keyboard.
You can use string. fromcharcode () to convert the key code to a verification code.
The table corresponding to the key code and secret code can be found at the end of this article.

 

Key value for letters and numbers)
Buttons	Key code	Buttons	Key code	Buttons	Key code	Buttons	Key code
A	65	J	74	S	83	1	49
B	66	K	75	T	84	2	50
C	67	L	76	U	85	3	51
D	68	M	77	V	86	4	52
E	69	N	78	W	87	5	53
F	70	O	79	X	88	6	54
G	71	P	80	Y	89	7	55
H	72	Q	81	Z	90	8	56
I	73	R	82	0	48	9	57

 

Keycode)				Function key value (keycode)
Buttons	Key code	Buttons	Key code	Buttons	Key code	Buttons	Key code
0	96	8	104	F1	112	F7	118
1	97	9	105	F2	113	F8	119
2	98	*	106	F3	114	F9	120
3	99	+	107	F4	115	F10	121
4	100	Enter	108	F5	116	F11	122
5	101	-	109	F6	117	F12	123
6	102	.	110
7	103	/	111

Key Value)
Buttons	Key code	Buttons	Key code	Buttons	Key code	Buttons	Key code
Backspace	8	ESC	27	Right arrow	39	-_	189
Tab	9	Spacebar	32	DW arrow	40	.>	190
Clear	12	Page up	33	Insert	45	/?	191
Enter	13	Page down	34	Delete	46	'~	192
Shift	16	End	35	Num Lock	144	[{	219
Control	17	Home	36	;:	186	\ |	220
ALT	18	Left arrow	37	= +	187	]}	221
Cape lock	20	Up Arrow	38	, </TD>	188	'"	222

 

Multimedia key value (keycode)
Buttons	Key code	Buttons	Key code	Buttons	Key code	Buttons	Key code
Volume increase	175
Volume reduction	174
Stop	179
Mute	173
Browser	172
Email	180
Search	170
favorites	171