c# - asp:TextBox 和 MaxLength

Question

我写了这个：

<asp:TextBox ID="txtSMSMessaggio" CssClass="inputForm" MaxLength="240" TextMode="MultiLine" runat="server"></asp:TextBox>

但在客户端我看不到属性 maxlength （我需要）。为什么？我该如何解决？

Answer 1

您可以只使用<textarea>标签并添加runat="server"吗？

<textarea id="txtSMSMessaggio" class="inputForm" maxlength="240" runat="server"></textarea>

Answer 2

您可能对计算 TextBox 中的字符不感兴趣，但它有助于让最终用户知道在达到限制之前存在限制。你可以做类似的事情

<script language="javascript" type="text/javascript">
var Maxlength = 240;
function taLimit() {
 var srcObject = event.srcElement;
 if (srcObject.value.length == Maxlength * 1) return false;
}

function taCount(tagName) {
 var srcObject = event.srcElement;
 if (srcObject.value.length > Maxlength * 1) srcObject.value = srcObject.value.substring(0, Maxlength * 1);
 if (tagName) visCnt.innerText = Maxlength - srcObject.value.length;
}
</script>

<asp:TextBox ID="txtSMSMessaggio" CssClass="inputForm" TextMode ="MultiLine" runat="server" 
onkeypress="return taLimit()" onkeyup="return taCount(Counter)" onfocus="return
taCount(Counter)" ></asp:TextBox><br />
(<span id="Counter">240</span> characters left)<br />

Answer 3

您可以尝试使用正则表达式将用户限制为 240 个字符：-

<asp:RegularExpressionValidator runat="server" ID="txtSMSMessaggio"
ControlToValidate="txtInput"
ValidationExpression="^[\s\S]{0,240}$"
ErrorMessage="Some error message"
Display="Dynamic">*</asp:RegularExpressionValidator>