Sunday, July 15, 2007

Javascript keyCode


<script type="text/javascript" charset="utf-8">
<!--
function doc (argument) {
document.write(argument);
document.write("<br />\n");
}

function isNumberInput(field, event)
{
var key, keyChar;
if (window.event) {
key = window.event.keyCode;
alert(key);
} else if (event) {
key = event.which;
code = event.keyCode;
var d1 = document.getElementById('d1');
d1.appendChild(document.createTextNode(key + "(key)=" + String.fromCharCode(event.which) + "(code) \n"));
// event.shiftKey and event.altKey, Mozilla provides a mapping for the keys, so you could do something. like:
if (event.keyCode == event.DOM_VK_TAB){
alert('TAB is pressed');
} else if (event.keyCode == event.DOM_VK_F1){
alert('F1 is pressed');
}
} else {
return true;
}
// Check for special characters like backspace(8), enter return(13), tab(9), escape(27) etc.
if (key == null || key == 0 || key == 8 || key == 13 || key == 27) {
return true;
}

// Check to see if it's a number
keyChar = String.fromCharCode(key);
if (/\d/.test(keyChar))
{
window.status = "";
return true;
}
else
{
window.alert("Field accepts numbers only.");
return false; // not input error keypress
}
}
//-->
</script>
<div id="d1">

</div>
<form name="testform" id="testform" action="#" method="get">
Robot Serial Number:
<input type="text" name="serialnumber" id="serialnumber" size="10" maxlength="10"
onkeypress="return isNumberInput(this, event);" title="Serial number contains only digits" />
</form>

Using Keyboard Events

Prior to the release of Netscape 4.0, JavaScript programs couldn't detect keyboard
actions—just mouse actions. This made it difficult to create some types of programs
in JavaScript. For example, games were difficult to play using Go Left and Go Right
buttons.

Thankfully, JavaScript 1.2 and later can detect keyboard actions. The main event
handler for this purpose is onKeyPress, which occurs when a key is pressed and
released, or held down. As with mouse buttons, you can detect the down and up parts
of the keypress with the onKeyDown and onKeyUp event handlers.

Of course, you may find it useful to know which key the user pressed. You can find
this out with the event object, which is sent to your event handler when the event
occurs. In Netscape, the event.which property stores the ASCII character code for the
key that was pressed. In Internet Explorer, event.keyCode serves the same purpose.

NOTE

ASCII (American Standard Code for Information Interchange) is the standard numeric
code used by most computers to represent characters. It assigns the numbers 0–128 to
various characters—for example, the capital letters A through Z are ASCII values 65
to 90.

Displaying Typed Characters

If you'd rather deal with actual characters than key codes, you can use the
fromCharCode string method to convert them. This method converts a numeric ASCII code
to its corresponding string character. For example, the following statement converts
Netscape's event.which property to a character and stores it in the key variable:

Key = String.fromCharCode(event.which);

Since Internet Explorer and Netscape have different ways of returning the key code,
displaying keys browser-independently is a bit harder. However, you can create a
script that displays keys for either browser. The following function will display
each key in the status line:

function DisplayKey(e) {
if (e.keyCode) keycode=e.keyCode;
else keycode=e.which;
character=String.fromCharCode(keycode);
window.status += character;
}

The DisplayKey function receives the event object from the event handler and stores
it in the variable e. It checks whether the e.keyCode property exists, and stores it
in the keycode variable if present. Otherwise, it assumes the browser is Netscape and
assigns keycode to the e.which property.

Key Pressed Javascript Key Code
backspace 8
tab 9
enter 13
shift 16
ctrl 17
alt 18
pause/break 19
caps lock 20
escape 27
page up 33
page down 34
end 35
home 36
left arrow 37
up arrow 38
right arrow 39
down arrow 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
f11 122
f12 123
num lock 144
scroll lock 145
semi-colon 186
equal sign 187
comma 188
dash 189
period 190
forward slash 191
grave accent 192
open bracket 219
back slash 220
close braket 221
single quote 222

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