JS获取按键的代码，Js如何屏蔽用户的按键

[From] http://www.zgguan.com/zsfx/jsjc/1181.html

在使用JavaScript做WEB键盘事件侦听捕获时，主要采用onkeypress，onkeydown，onkeyup三个事件，这三个事件执行的顺序为：onkeydown，onkeypress，onkeyup，在一般情况下，采用三种键盘事件均可对键盘输入进行有效的响应，但实际应用的时候会有些许差异，onkeypress事件不能对系统功能键（例如：删除，后退等，其中对中文输入法不能有效的响应）进行正常的响应，onkeydown和onkeyup均可以对系统功能键进行有效的拦截，但事件捕获的位置不同，可以根据具体的情况选择不同的键盘事件。

由于onkeypress不能对系统功能键进行捕获，导致window.event对象的keyCode属性和onkeydown，onkeyup键盘事件中获取的keyCode属性不同，主要表现在onkeypress事件的keyCode对字母的大小写敏感，而onkeydown、onkeyup事件不敏感；onkeypress事件的keyCode无法区分主键盘上的数字键和付键盘数字键的，而onkeydown、onkeyup的keyCode对主付键盘的数字键敏感。

js判断用户按下的按键，根据按下的按键然后执行不同的操作：

document.body.onkeydown=window.onkeydown=function(e){
	var keyCode;
	if(!e) e=window.event;
	if(document.all){
		keyCode=e.keyCode;
	}else{
		keyCode=e.which;
	}
	if(keyCode==37){
		window.location.href="http://www.zgguan.com";
	}
	if(keyCode==39||keyCode==13){
		window.location.href="http://www.zgguan.com";
	}
}

js如何屏蔽用户输入的各种按键呢？请看下面的例子：

function KeyDown(){
	if((window.event.altKey)&&((window.event.keyCode==37)||(window.event.keyCode==39))){
		//屏蔽 Alt+ 方向键 → alert("不准你使用ALT+方向键前进或后退网页！");
		event.returnValue=false;
	}
	if((event.keyCode==8)||(event.keyCode==116)){
		//屏蔽 F5 刷新键
		event.keyCode=0;
		event.returnValue=false;
	}
	if((event.ctrlKey)&&(event.keyCode==78)){
		//屏蔽 Ctrl+n
		event.returnValue=false;
	}
	if((event.shiftKey)&&(event.keyCode==121)){
		//屏蔽 shift+F10
		event.returnValue=false;
	}if(event.keyCode==122){
		//屏蔽 F11
		event.returnValue=false;
	}
}

键盘各种按键对应的ASII码如下：

keycode 8 = BackSpace BackSpace

keycode 9 = Tab Tab

keycode 12 = Clear

keycode 13 = Enter

keycode 16 = Shift_L

keycode 17 = Control_L

keycode 18 = Alt_L

keycode 19 = Pause

keycode 20 = Caps_Lock

keycode 27 = Escape Escape

keycode 32 = space space

keycode 33 = Prior

keycode 34 = Next

keycode 35 = End

keycode 36 = Home

keycode 37 = Left

keycode 38 = Up

keycode 39 = Right

keycode 40 = Down

keycode 41 = Select

keycode 42 = Print

keycode 43 = Execute

keycode 45 = Insert

keycode 46 = Delete

keycode 47 = Help

keycode 48 = 0 equal braceright

keycode 49 = 1 exclam onesuperior

keycode 50 = 2 quotedbl twosuperior

keycode 51 = 3 section threesuperior

keycode 52 = 4 dollar

keycode 53 = 5 percent

keycode 54 = 6 ampersand

keycode 55 = 7 slash braceleft

keycode 56 = 8 parenleft bracketleft

keycode 57 = 9 parenright bracketright

keycode 65 = a A

keycode 66 = b B

keycode 67 = c C

keycode 68 = d D

keycode 69 = e E EuroSign

keycode 70 = f F

keycode 71 = g G

keycode 72 = h H

keycode 73 = i I

keycode 74 = j J

keycode 75 = k K

keycode 76 = l L

keycode 77 = m M mu

keycode 78 = n N

keycode 79 = o O

keycode 80 = p P

keycode 81 = q Q at

keycode 82 = r R

keycode 83 = s S

keycode 84 = t T

keycode 85 = u U

keycode 86 = v V

keycode 87 = w W

keycode 88 = x X

keycode 89 = y Y

keycode 90 = z Z

keycode 96 = KP_0 KP_0

keycode 97 = KP_1 KP_1

keycode 98 = KP_2 KP_2

keycode 99 = KP_3 KP_3

keycode 100 = KP_4 KP_4

keycode 101 = KP_5 KP_5

keycode 102 = KP_6 KP_6

keycode 103 = KP_7 KP_7

keycode 104 = KP_8 KP_8

keycode 105 = KP_9 KP_9

keycode 106 = KP_Multiply KP_Multiply

keycode 107 = KP_Add KP_Add

keycode 108 = KP_Separator KP_Separator

keycode 109 = KP_Subtract KP_Subtract

keycode 110 = KP_Decimal KP_Decimal

keycode 111 = KP_Divide KP_Divide

keycode 112 = F1

keycode 113 = F2

keycode 114 = F3

keycode 115 = F4

keycode 116 = F5

keycode 117 = F6

keycode 118 = F7

keycode 119 = F8

keycode 120 = F9

keycode 121 = F10

keycode 122 = F11

keycode 123 = F12

keycode 124 = F13

keycode 125 = F14

keycode 126 = F15

keycode 127 = F16

keycode 128 = F17

keycode 129 = F18

keycode 130 = F19

keycode 131 = F20

keycode 132 = F21

keycode 133 = F22

keycode 134 = F23

keycode 135 = F24

keycode 136 = Num_Lock

keycode 137 = Scroll_Lock

keycode 187 = acute grave

keycode 188 = comma semicolon

keycode 189 = minus underscore

keycode 190 = period colon

keycode 192 = numbersign apostrophe

keycode 210 = plusminus hyphen macron

keycode 211 =

keycode 212 = copyright registered

keycode 213 = guillemotleft guillemotright

keycode 214 = masculine ordfeminine

keycode 215 = ae AE

keycode 216 = cent yen

keycode 217 = questiondown exclamdown

keycode 218 = onequarter onehalf threequarters

keycode 220 = less greater bar

keycode 221 = plus asterisk asciitilde

keycode 227 = multiply division

keycode 228 = acircumflex Acircumflex

keycode 229 = ecircumflex Ecircumflex

keycode 230 = icircumflex Icircumflex

keycode 231 = ocircumflex Ocircumflex

keycode 232 = ucircumflex Ucircumflex

keycode 233 = ntilde Ntilde

keycode 234 = yacute Yacute

keycode 235 = oslash Ooblique

keycode 236 = aring Aring

keycode 237 = ccedilla Ccedilla

keycode 238 = thorn THORN

keycode 239 = eth ETH

keycode 240 = diaeresis cedilla currency

keycode 241 = agrave Agrave atilde Atilde

keycode 242 = egrave Egrave

keycode 243 = igrave Igrave

keycode 244 = ograve Ograve otilde Otilde

keycode 245 = ugrave Ugrave

keycode 246 = adiaeresis Adiaeresis

keycode 247 = ediaeresis Ediaeresis

keycode 248 = idiaeresis Idiaeresis

keycode 249 = odiaeresis Odiaeresis

keycode 250 = udiaeresis Udiaeresis

keycode 251 = ssharp question backslash

keycode 252 = asciicircum degree

keycode 253 = 3 sterling

keycode 254 = Mode_switch

使用event对象的keyCode属性判断输入的键值

eg：if(event.keyCode==13)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　 0　　 0X48

H　　0X72　 1　　 0X49

I　　0X73　 2　　 0X50

J　　0X74　 3 　　0X51

K　　0X75　 4 　　0X52

L　　0X76　 5 　　0X53

M　　0X77　 6　　 0X54

N　　0X78 　7 　　0X55

O　　0X79 　8 　　0X56

P　　0X80 　9 　　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，则可以利用event.ctrlKey，event.shiftKey，event .altKey判断是否按下了ctrl键、shift键以及alt键