JS的event对象

Event属性和方法:

1. type:事件的类型,如onlick中的click;

2. srcElement/target:事件源,就是发生事件的元素;

3. button:声明被按下的鼠标键,整数,1代表左键,2代表右键,4代表中键,如果按下多个键,酒把这些值加起来,所以3就代表左右键同时按下;(firefox中 0代表左键,1代表中间键,2代表右键)

4. clientX/clientY:事件发生的时候,鼠标相对于浏览器窗口可视文档区域的左上角的位置;(在DOM标准中,这两个属性值都不考虑文档的滚动情况,也就是说,无论文档滚动到哪里,只要事件发生在窗口左上角,clientX和clientY都是 0,所以在IE中,要想得到事件发生的坐标相对于文档开头的位置,要加上
document.body.scrollLeft和 document.body.scrollTop)

5. offsetX,offsetY/layerX,layerY:事件发生的时候,鼠标相对于源元素左上角的位置;

6. x,y/pageX,pageY:检索相对于父要素鼠标水平坐标的整数;

7. altKey,ctrlKey,shiftKey等:返回一个布尔值;

8. keyCode:返回keydown何keyup事件发生的时候按键的代码,以及keypress 事件的Unicode字符;(firefox2不支持 event.keycode,可以用 event.which替代 )

9. fromElement,toElement:前者是指代mouseover事件中鼠标移动过的文档元素,后者指代mouseout事件中鼠标移动到的文档元素;

10. cancelBubble:一个布尔属性,把它设置为true的时候,将停止事件进一步起泡到包容层次的元素;(e.cancelBubble = true; 相当于 e.stopPropagation();)

11. returnValue:一个布尔属性,设置为false的时候可以组织浏览器执行默认的事件动作;(e.returnValue = false; 相当于 e.preventDefault();)

12. attachEvent(),detachEvent()/addEventListener(),removeEventListener:为制定 DOM对象事件类型注册多个事件处理函数的方法,它们有两个参数,第一个是事件类型,第二个是事件处理函数。在
attachEvent()事件执行的时候,this关键字指向的是window对象,而不是发生事件的那个元素;

13. screenX、screenY:鼠标指针相对于显示器左上角的位置,如果你想打开新的窗口,这两个属性很重要;


一些说明:

1.  event代表事件的状态,例如触发event对象的元素、鼠标的位置及状态、按下的键等等;

2.  event对象只在事件发生的过程中才有效。
firefox里的event跟IE里的不同,IE里的是全局变量,随时可用;firefox里的要用参数引导才能用,是运行时的临时变量。
在IE/Opera中是window.event,在Firefox中是event;而事件的对象,在IE中是 window.event.srcElement,在Firefox中是event.target,Opera中两者都可用。

3.  下面两句效果相同
var evt = (evt) ? evt : ((window.event) ? window.event : null);
var evt = evt || window.event; // firefox下window.event为null, IE下event为null

4.  IE中事件的起泡
IE中事件可以沿着包容层次一点点起泡到上层,也就是说,下层的DOM节点定义的事件处理函数,到了上层的节点如果还有和下层相同事件类型的事件处理函数,那么上层的事件处理函数也会执行。例如, div 标签包含了 a ,如果这两个标签都有onclick事件的处理函数,那么执行的情况就是先执行标签 a 的onclick事件处理函数,再执行 div 的事件处理函数。如果希望的事件处理函数执行完毕之后,不希望执行上层的 div 的onclick的事件处理函数了,那么就把cancelBubble设置为true即可。

js event.keyCode对应的键码:

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

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.