JS KeyUp, KeyPress and KeyDown events

Reproduced from: http://www.cnblogs.com/manongxiaobing/archive/2012/11/05/2755412.html

JS KeyUp, KeyPress, and KeyDown events are all about keyboard events

When a button is pressed or released in every modern browser, there can be three kinds of client events. KeyDown event KeyPress Event KeyUp Event

The KeyDown event occurs when the key of the keyboard is pressed, and then the KeyPress event is triggered. The KeyUp event is triggered when the key is released.

Examples of how these three events are used in the page are as follows:

<input id= "testkeyevent" name= "testkeyevent" onKeyUp = "KeyUp ()"/>

<input id= "testkeyevent" name= "testkeyevent" onkeypress = "keypress ()"/>

<input id= "testkeyevent" name= "testkeyevent" onkeydown = "KeyDown ()"/>

The corresponding JS function:

function KeyUp () {...}

function KeyPress () {...}

function KeyDown () {...}

Note: After the KeyDown trigger, the KeyUp is not necessarily triggered, and when KeyDown is pressed, drag the mouse, then the KeyUp event will not be triggered. KeyPress is primarily used to capture numbers ( Note: Symbols that include shift+ numbers ), letters ( Note: include case ), keypad, and so on except f1-12, SHIFT, Alt, Ctrl, Insert, home, PgUp, The ANSI characters KeyDown and KeyUp outside the Delete, end, PgDn, ScrollLock, Pause, NumLock, {Menu key}, {Start key}, and directional keys can usually capture the keyboard except PRSCRN all keys ( This does not discuss special keys for special keyboards) KeyPress can only capture single characters KeyDown and KeyUp to capture key combinations. KeyPress can capture the case of a single character KeyDown and KeyUp the keyvalue captured for a single character is a value, that is, the case of a single character cannot be judged. KeyPress does not distinguish between numeric characters of the keypad and the main keyboard. KeyDown and KeyUp distinguish the numeric characters of the keypad and the main keyboard. None of the Prscrn buttons KeyPress, KeyDown, and KeyUp can be captured.

When you use the keyboard, you will typically use a key combination function similar to Ctrl+shift+alt. How do we determine that?

Can be handled through the KeyUp event (here's why you don't need to KeyDown, because when you decide KeyDown, CTRL, Shift, and ALT belong to the pressed state, and then another key is not exactly capturing the key combination, so use the KeyDown Can not be accurately judged by the KeyUp event to determine.

Here is a simple list of CTRL + other key combinations to determine the code:
private void Form3_keyup (object sender, KeyEventArgs e)
{
if (E.control)
{
MessageBox.Show ("keyup:ctrl+" + e.keyvalue.tostring ());
}
Capture Prscrn Key Event

A hook can be used to determine the PRSCRN key event, and the hook gets any keyboard events.

Here are the code for some keys on the keyboard: Here are the code for some keys on the keyboard:

keyboard keys corresponding to the digital

Backspace	8
tab	9
Enter	13
Shift	16
Ctrl	17
Alt	18
Pause/break	19
Caps LOCK	20
Escape	27
Page UP	33
MySpace	32
Page Down	34
End	35
Home	36
Arrow Left	37
Arrow up	38
Arrow Right	39
Arrow Down	40
Insert	45
Delete	46
0	48
1	49
2	50
3	51
4	52
5	53
6	54
7	55
8	56
9	57
A	65
B	66
C	67
D	68
E	69
F	70
G	71
H	72
I	73
J	74
K	75
L	76
M	77
N	78
O	79
P	80
Q	81
R	82
S	83
T	84
U	85
V	86
W	87
X	88
Y	89
Z	90
Left window key	91
Right window key	92
Select key	93
Numpad 0	96
Numpad 1	97
Numpad 2	98
Numpad 3	99
Numpad 4	100
Numpad 5	101
Numpad 6	102
Numpad 7	103
Numpad 8	104
Numpad 9	105
Multiply	106
Add	107
Subtract	109
decimal point	110
Divide	111
F1	112
F2	113
F3	114
F4	115
F5	116
F6	117
F7	118
F8	119
F9	120
F10	121
F1