sash003, проверьте здесь
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
</head>
<body> <input name="">
<script>
var input = document.querySelector('input') ;
addEvent(input, 'keypress', function(e){
e = e || window.event;
if(
!(/ |\d|\+/.test(String.fromCharCode(e.charCode||e.keyCode)))
){
if(e.preventDefault) e.preventDefault();
else e.returnValue = false;
}
});
function addEvent(elem, type, handler, param){
param = param || false;
if(elem.addEventListener){
elem.addEventListener(type, handler, param);
} else {
elem.attachEvent('on'+type, handler);
}
return false;
}
</script>
</body>
</html>