方法一:弹出对话框提示
1.html代码
<HTML>
<HEAD>
<title>WebForm6</title>
<metaname="GENERATOR"Content="7.1">
<metaname="CODE_LANGUAGE"Content="C#">
<metaname="vs_defaultClientScript"content="JavaScript">
<metaname="vs_targetSchema"content="/intellisense/ie5">
<scriptlanguage="javascript">
functionisOver(sText,len)
{
varintlen=sText.value.length;
if(intlen>len)
{
alert("ThecontentlengthmustLessthanorEqual"+len);
sText.focus();
sText.select();
}
}
</script>
</HEAD>
<bodyMS_POSITIONING="GridLayout">
<formid="Form1"method="post"runat="server">
<asp:TextBoxid="txtName"style="Z-INDEX:102;LEFT:200px;POSITION:absolute;TOP:104px"runat="server"
TextMode="MultiLine"Height="112px"Width="271px"></asp:TextBox>
</form>
</body>
</HTML>2.cs代码
privatevoidPage_Load(objectsender,System.EventArgse)
{
this.txtName.Attributes.Add("onblur","isOver(this,1000);");
}方法二:限制用户继续输入
<HEAD>
<!--TWOSTEPSTOINSTALLLIMITTEXTAREA:
1.CopythecodingintotheHEADofyourHTMLdocument
2.AddthelastcodeintotheBODYofyourHTMLdocument-->
<!--STEPONE:PastethiscodeintotheHEADofyourHTMLdocument-->
<SCRIPTLANGUAGE="JavaScript">
<!--Original:RonnieT.Moore-->
<!--WebSite:TheJavaScriptSource-->
<!--Dynamic'fix'by:NannetteThacker-->
<!--WebSite:-->
<!--Thisscriptandmanymoreareavailablefreeonlineat-->
<!--TheJavaScriptSource!!-->
<!--Begin
functiontextCounter(field,countfield,maxlimit){
if(field.value.length>maxlimit)//iftoolongtrimit!
field.value=field.value.substring(0,maxlimit);
//otherwise,update'charactersleft'counter
else
countfield.value=maxlimit-field.value.length;
}
//End-->
</SCRIPT>
<!--STEPTWO:CopythiscodeintotheBODYofyourHTMLdocument-->
</HEAD>
<BODY>
<!--textCounter()parametersare:textfield,thecountfield,maxlength-->
<center>
<formname="myform"action="YOUR-SCRIPT.CGI">
<fontsize="1"face="arial,helvetica,sans-serif">(Youmayenterupto125
characters.)<br>
<textareaname="message"wrap="physical"cols="28"rows="4"onKeyDown="textCounter(this.form.message,this.form.remLen,125);"
onKeyUp="textCounter(this.form.message,this.form.remLen,125);"></textarea>
<br>
<inputreadonlytype="text"name="remLen"size="3"maxlength="3"value="125">characters
left</font>
</form>
</center>
<p><center>
<fontface="arial,helvetica"SIZE="-2">FreeJavaScriptsprovided<br>
by<ahref="">TheJavaScriptSource</a></font>
</center>
</BODY>