使用方法：
<script type="text/javascript" language=JavaScript charset="UTF-8">
document.onkeydown=function(event){
var e = event || window.event || arguments.callee.caller.arguments[];
if(e && e.keyCode==){ // 按 Esc
//要做的事情
}
if(e && e.keyCode==){ // 按 F2
//要做的事情
}
if(e && e.keyCode==){ // enter 键
//要做的事情
}
};
</script>
只要你定义了这些键的动作，你在浏览器里按下这些键就会响应，兼容目前所有浏览器。
参考目录：
js 里面的键盘事件经常用到，所以收集了键盘事件对应的键码来分享下：
keyCode = BackSpace BackSpace
keyCode = Tab Tab
keyCode = Clear
keyCode = Enter
keyCode = Shift_L
keyCode = Control_L
keyCode = Alt_L
keyCode = Pause
keyCode = Caps_Lock
keyCode = Escape Escape
keyCode = space
keyCode = Prior
keyCode = Next
keyCode = End
keyCode = Home
keyCode = Left
keyCode = Up
keyCode = Right
keyCode = Down
keyCode = Select
keyCode = Print
keyCode = Execute
keyCode = Insert
keyCode = Delete
keyCode = Help
keyCode = equal braceright
keyCode = exclam onesuperior
keyCode = quotedbl twosuperior
keyCode = section threesuperior
keyCode = dollar
keyCode = percent
keyCode = ampersand
keyCode = slash braceleft
keyCode = parenleft bracketleft
keyCode = parenright bracketright
keyCode = a A
keyCode = b B
keyCode = c C
keyCode = d D
keyCode = e E EuroSign
keyCode = f F
keyCode = g G
keyCode = h H
keyCode = i I
keyCode = j J
keyCode = k K
keyCode = l L
keyCode = m M mu
keyCode = n N
keyCode = o O
keyCode = p P
keyCode = q Q at
keyCode = r R
keyCode = s S
keyCode = t T
keyCode = u U
keyCode = v V
keyCode = w W
keyCode = x X
keyCode = y Y
keyCode = z Z
keyCode = KP_0 KP_0
keyCode = KP_1 KP_1
keyCode = KP_2 KP_2
keyCode = KP_3 KP_3
keyCode = KP_4 KP_4
keyCode = KP_5 KP_5
keyCode = KP_6 KP_6
keyCode = KP_7 KP_7
keyCode = KP_8 KP_8
keyCode = KP_9 KP_9
keyCode = KP_Multiply KP_Multiply
keyCode = KP_Add KP_Add
keyCode = KP_Separator KP_Separator
keyCode = KP_Subtract KP_Subtract
keyCode = KP_Decimal KP_Decimal
keyCode = KP_Divide KP_Divide
keyCode = F1
keyCode = F2
keyCode = F3
keyCode = F4
keyCode = F5
keyCode = F6
keyCode = F7
keyCode = F8
keyCode = F9
keyCode = F10
keyCode = F11
keyCode = F12
keyCode = F13
keyCode = F14
keyCode = F15
keyCode = F16
keyCode = F17
keyCode = F18
keyCode = F19
keyCode = F20
keyCode = F21
keyCode = F22
keyCode = F23
keyCode = F24
keyCode = Num_Lock
keyCode = Scroll_Lock
keyCode = acute grave
keyCode = comma semicolon
keyCode = minus underscore
keyCode = period colon
keyCode = numbersign apostrophe
keyCode = plusminus hyphen macron
keyCode =
keyCode = copyright registered
keyCode = guillemotleft guillemotright
keyCode = masculine ordfeminine
keyCode = ae AE
keyCode = cent yen
keyCode = questiondown exclamdown
keyCode = onequarter onehalf threequarters
keyCode = less greater bar
keyCode = plus asterisk asciitilde
keyCode = multiply division
keyCode = acircumflex Acircumflex
keyCode = ecircumflex Ecircumflex
keyCode = icircumflex Icircumflex
keyCode = ocircumflex Ocircumflex
keyCode = ucircumflex Ucircumflex
keyCode = ntilde Ntilde
keyCode = yacute Yacute
keyCode = oslash Ooblique
keyCode = aring Aring
keyCode = ccedilla Ccedilla
keyCode = thorn THORN
keyCode = eth ETH
keyCode = diaeresis cedilla currency
keyCode = agrave Agrave atilde Atilde
keyCode = egrave Egrave
keyCode = igrave Igrave
keyCode = ograve Ograve otilde Otilde
keyCode = ugrave Ugrave
keyCode = adiaeresis Adiaeresis
keyCode = ediaeresis Ediaeresis
keyCode = idiaeresis Idiaeresis
keyCode = odiaeresis Odiaeresis
keyCode = udiaeresis Udiaeresis
keyCode = ssharp question backslash
keyCode = asciicircum degree
keyCode = sterling
keyCode = Mode_switch
使用event对象的keyCode属性判断输入的键值
eg：if(event.keyCode==)alert(“enter!”);
键值对应表
A 0X65 U 0X85
B 0X66 V 0X86
C 0X67 W 0X87
D 0X68 X 0X88
E 0X69 Y 0X89
F 0X70 Z 0X90
G 0X71 0X48
H 0X72 0X49
I 0X73 0X50
J 0X74 0X51
K 0X75 0X52
L 0X76 0X53
M 0X77 0X54
N 0X78 0X55
O 0X79 0X56
P 0X80 0X57
Q 0X81 ESC 0X1B
R 0X82 CTRL 0X11
S 0X83 SHIFT 0X10
T 0X84 ENTER 0XD
如果要使用组合键，则可以判断是否同时按下了这几个键，比如ctrl键、shift键以及alt键的组合使用就可以判断是否多按下了ctrl键、shift键以及alt键
