只能输入数字
<input onkeypress="return event.keyCode>=48&&event.keyCode<=57||event.keyCode==46" onpaste="return !clipboardData.getData('text').match(/\D/)" ondragenter="return false">
<input onkeypress="return event.keyCode>=48&&event.keyCode<=57||event.keyCode==46" onpaste="return !clipboardData.getData('text').match(/\D/)" ondragenter="return false">
<input onkeypress="return (event.keyCode>96&&event.keyCode<123)||(event.keyCode>64&&event.keyCode<91)" onpaste="return !clipboardData.getData('text').match(/\D/)" ondragenter="return false">