在做網頁的時候，有時是需要js來判斷使用者的按鍵來進行操作對應的功能。
本例項已載入jquery.js

1、全域性判斷按鍵（按回車）

$(document).keypress(function(e) {
       var eCode = e.keyCode ? e.keyCode : e.which ? e.which : e.charCode;
        if (eCode == 13){
            alert('您按了回車鍵')
            //自己寫判斷操作
        }
});

2、給某個元素（按回車）

$("input[name=keyword]"
 
).keypress(function(e){
        var eCode = e.keyCode ? e.keyCode : e.which ? e.which : e.charCode;
        if (eCode == 13){
            alert('您按了回車鍵')
            //自己寫判斷函式
        }
})

這裡的13對應的鍵就是回車鍵。

以下是組合按鍵的應用：

if(e.altKey && e.keyCode==13){
    alert('您同時按了Alt鍵和Enter鍵')
        //ctrl鍵是e.ctrlKey
 

        //shift鍵是e.shiftKey
    }
});

以下是單個按鍵對應的數字,建議使用keyup,keypress在某些瀏覽器不生效：

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 on esuperior
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 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

Javascript中 有3個事件控制代碼在對應鍵盤的輸入狀態：keydown、keypress和keyup。
分別對應的意思是：按鍵被按下（按下按鍵但還沒有擡起）、點選按鍵（按下並擡起按鍵）、按鍵擡起（按鍵擡起之後）

按鍵的分類:

按鍵可以分為“實鍵”和“虛鍵”
實鍵可以理解為我們能夠看到並打印出來的按鍵，如字母“A”、數字“1”、字元“?”等等
虛鍵就是那些無法打印出來起到控制作用的按鍵，如“Ctrl”、“Alt”、“Shift”、“方向鍵”等等
IE在處理虛鍵時有個特例：虛鍵不會產生keypress事件，必須使用keydown或keyup來捕獲

按鍵碼和字元碼

按鍵碼是計算機用來識別不同按鍵的編碼，每一個按鍵都有按鍵碼
字元碼是可被列印的實鍵特有的，對應了鍵盤上顯示的字元
按鍵碼可以使用String.fromCharCode()轉換為字元碼
按鍵碼和和字元碼的對應表可以在本文最後找到。

獲取實鍵

$('body').bind('keypress',getKeyCode);   
function getKeyCode(e) {  
    var evt = e || window.event;  
    var keyCode = evt.keyCode || evt.which || evt.charCode;  
    alert(keyCode);  
}  

稍微解釋下
1. e為Firefox等標準瀏覽器支援的JS隱藏變數，表示一個“事件”；IE系列中沒有“e”，而是用window.event來表示“事件”；所以var e = e || window.event;就表示：獲取當前正在發生的事件。
2. e.keyCode、e.which、e.charCode都代表獲取按鍵碼，但不同的瀏覽器支援不同的寫法

獲取虛鍵

function getKeyCode(e) {  
    var evt = e || window.event;  
    if (evt.ctrlKey) alert("ctrlKey pressed");  
    if (evt.altKey) alert("altKey pressed");  
    if (evt.shiftKey) alert("shiftKey pressed");  
}  

字母和數字鍵的鍵碼值(keyCode)