Validating input characters for numbers using javascript

Javascript code:

function isNumeric()

{

if(((window.event.keyCode >= 48) && (window.event.keyCode <= 57)) || ((window.event.keyCode >= 96) && (window.event.keyCode <= 105)) || ((window.event.keyCode == 8) || (window.event.keyCode == 9) || (window.event.keyCode == 46) || (window.event.keyCode == 35) || (window.event.keyCode == 36) || (window.event.keyCode == 37) || (window.event.keyCode == 39)))

{

return true;

}

else

{

return false;

}

}