js验证表单的例子，js表单提交时的输入验证检测

<script language="javascript">
function checkform(obj)
{
for(i=0;i<obj.oo.length;i++)
if(obj.oo[i].checked==true) return true;

alert("请选择")
return false;  

}
</script>
<form id="form1" name="form1" method="post" action=""   onsubmit="return checkform(this)">
   <input type="radio" name="oo" value="radiobutton" />
   <input type="radio" name="oo" value="radiobutton" />
   <input type="submit" name="Submit" value="提交" />
</form>

<script>
function test()
{
if(document.a.b.value.length>50)
{
alert("不能超过50个字符！");
document.a.b.focus();
return false;
}
}
</script>
<form name=a onsubmit="return test()">
<textarea name="b" cols="40" wrap="VIRTUAL" rows="6"></textarea>
<input type="submit" name="Submit" value="check">
</form>

<script language=javascript>
function onlyEng()
{
if(!(event.keyCode>=65&&event.keyCode<=90))
event.returnvalue=false;
}
</script>

<input onkeydown="onlyEng();">

<script language=javascript>
function onlyNum()
{
if(!((event.keyCode>=48&&event.keyCode<=57)||(event.keyCode>=96&&event.keyCode<=105)))
//考虑小键盘上的数字键
event.returnvalue=false;
}
</script>

<input onkeydown="onlyNum();">

<input onkeyup="value="/oblog/value.replace(/[W]/g,"'') "onbeforepaste="clipboardData.setData('text',clipboardData.getData('text').replace(/[^d]/g,''))">

<SCRIPT LANGUAGE=javascript RUNAT=Server>
function isEmail(strEmail) {
if (strEmail.search(/^w+((-w+)|(.w+))*@[A-Za-z0-9]+((.|-)[A-Za-z0-9]+)*.[A-Za-z0-9]+$/) != -1)
return true;
else
alert("oh");
}
</SCRIPT>
<input type=text onblur=isEmail(this.value)>

<script language="javascript1.2">
function test() {
if((a.b.value.indexOf ("***") == 0)||(a.b.value.indexOf ("****") == 0)){
alert("");
a.b.focus();
return false;}
}
</script>
<form name=a onsubmit="return test()">
<input type=text name=b>
<input type="submit" name="Submit" value="check">
</form>

<FORM METHOD=POST ACTION="">
<input type="password" id="input1">
<input type="password" id="input2">
<input type="button" value="test" onclick="check()">
</FORM>
<script>
function check()
{
with(document.all){
if(input1.value!=input2.value)
{
alert("false")
input1.value = "";
input2.value = "";
}
else document.forms[0].submit();
}
}
</script>
屏蔽右键：
oncontextmenu="return false" ondragstart="return false" onselectstart="return false"
加在body中

<script  language="javascript">
<!--
functionisEnglish(name)//英文值检测
{ 
if(name.length==0)
returnfalse;
for(i=0;i<name.length;i++)
{ 
if(name.charCodeAt(i)>128)
returnfalse;
}
returntrue;
}

functionisChinese(name)//中文值检测
{ 
if(name.length==0)
returnfalse;
for(i=0;i<name.length;i++){ 
if(name.charCodeAt(i)>128)
returntrue;
}
returnfalse;
}

functionisMail(name)//E-mail值检测
{ 
if(!isEnglish(name))
returnfalse;
i=name.indexOf("at");
j=namedotlastIndexOf("at");
if(i==-1)
returnfalse;
if(i!=j)
returnfalse;
if(i==namedotlength)
returnfalse;
returntrue;
}

functionisNumber(name)//数值检测
{ 
if(name.length==0)
returnfalse;
for(i=0;i<name.length;i++){ 
if(name.charAt(i)<"0"||name.charAt(i)>"9")
returnfalse;
}
returntrue;
}

functionCheckForm()
{ 
if(!isMail(form.Email.value)){ 
alert("您的电子邮件不合法！");
form.Email.focus();
returnfalse;
}
if(!isEnglish(form.name.value)){ 
alert("英文名不合法！");
form.name.focus();
returnfalse;
}
if(!isChinese(form.cnname.value)){ 
alert("中文名不合法！");
form.cnname.focus();
returnfalse;
}
if(!isNumber(form.PublicZipCode.value)){ 
alert("邮政编码不合法！");
form.PublicZipCode.focus();
returnfalse;
}
returntrue;
}
//-->
</SCRIPT>

<scriptlanguage="javascript">
<!--
functioncontain(str,charset)//字符串包含测试函数
{ 
vari;
for(i=0;i<charset.length;i++)
if(str.indexOf(charset.charAt(i))>=0)
returntrue;
returnfalse;
}

functionCheckForm()
{ 
if((contain(document.form.NAME.value,"%()><"))||(contain(document.form.MESSAGE.value,"%()><")))
{ 
alert("输入了非法字符");
document.form.NAME.focus();
returnfalse;
}
returntrue;
}
//-->
</script>