兼容IE和Firefox

判断浏览器类型:
<script language="JavaScript">
<!--
function getOs()
{
var OsObject = "";
if(navigator.userAgent.indexOf("MSIE")>0) {
return "MSIE";
}
if(isFirefox=navigator.userAgent.indexOf("Firefox")>0){
return "Firefox";
}
if(isSafari=navigator.userAgent.indexOf("Safari")>0) {
return "Safari";
}
if(isCamino=navigator.userAgent.indexOf("Camino")>0){
return "Camino";
}
if(isMozilla=navigator.userAgent.indexOf("Gecko/")>0){
return "Gecko";
}

}
alert("您的浏览器类型为:"+getOs());
-->
</script>

======================================
限制input只能输入数字(兼容IE和Firefox):
isNumber = function (e) {
if (navigator.userAgent.indexOf("MSIE")>0) {
if ( ((event.keyCode > 47) && (event.keyCode < 58)) ||
(event.keyCode == 8) ) {
return true;
} else {
return false;
}
} else {
if ( ((e.which > 47) && (e.which < 58)) ||
(e.which == 8) ) {
return true;
} else {
return false;
}
}
}

<input type='text' name='page' onkeypress="javascript:return isNumber(event);" />
=====================================
限制textarea输入长度 (For: IE、Firefox ...):
function isMaxLen(o){
var nMaxLen=o.getAttribute? parseInt(o.getAttribute("maxlength")):"";
if(o.getAttribute && o.value.length>nMaxLen){
o.value=o.value.substring(0,nMaxLen)
}
}

<textarea maxlength="20" onkeyup="return isMaxLen(this)">