Numeric Validation Using JavaScript

For allowing only numeric values to be placed inside a text box using JavaScript, we need to capture the “onKeyDown” event for the keyboard. This check is done on client side whenever a user enters a value in the textbox using keyboard keys.

Example of such a script is:

TextBoxTest.Attributes.Add(“onKeyDown”, “if((event.keyCode >= 48 && event.keyCode <= 57)||(event.keyCode >= 96 && event.keyCode <= 105)||(event.keyCode == 8 ) ||(event.keyCode == 9) || (event.keyCode == 12) || (event.keyCode == 27) || (event.keyCode == 37) || (event.keyCode == 39) || (event.keyCode == 46) ){return true;}else{return false;}”);

The keycodes used in the above example are deciphered below:

keycode  48 = 0
keycode  49 = 1
keycode  50 = 2 
keycode  51 = 3 
keycode  52 = 4
keycode  53 = 5
keycode  54 = 6
keycode  55 = 7 
keycode  56 = 8 
keycode  57 = 9 

keycode  96 = NumPad 0
keycode  97 = NumPad 1
keycode  98 = NumPad 2 
keycode  99 = NumPad 3 
keycode  100 =NumPad  4
keycode  101= NumPad 5
keycode  102= NumPad 6
keycode  103= NumPad 7 
keycode  104 = NumPad 8 
keycode  105 = NumPad 9 

keycode   8 = BackSpace
keycode   9 = Tab

keycode  12 = Clear

keycode  27 = Escape

keycode  37 = Left
keycode  39 = Right
keycode  46 = Delete

~ by Neha Sinha on January 30, 2008.