js限制input输入框只能输入数字

<input type="text" style="ime-mode:disabled;" onpaste="return false;"  onkeypress="keyPress()" />
function keyPress() {
var keyCode = event.keyCode;
if ((keyCode >= 48 && keyCode <= 57))
{
event.returnValue = true;
 } else {
event.returnValue = false;
} // www.jb200.com
}