在 jQuery 中获取文本框值

Question

No matter what I've tried, I cannot get the value of a textbox in my jQuery function. I know there is a value there, I can see it. However my code below comes back at "undefined" for the value. I cannot figure out why.

I have a js file that is referenced on my asp.net page. On my asp.net page, I have a button that triggers a function on click.

 <asp:ImageButton ID="BtnNext" runat="server" OnClientClick="TransactionType(); return false;" ImageUrl="~/next.png" />

My jQuery code:

function TransactionType() {
    var PType = $("#TxtPTypeValue").val;

    alert(PType);

    if (PType == "CC") {
        SubmitCCTransaction();
    } else if (PType == "EC") {
        SubmitECheckTransaction();
    };

};

The part that isn't working is this: var PType = $("#TxtPTypeValue").val; which comes back as "undefined".

Answer 1

You can fix in this way

$("#TxtPTypeValue").val();

 $("#BtnNext").on("click", function(){ console.log($("#TxtPTypeValue").val()); });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <input type = "text" id = "TxtPTypeValue" /> <button id="BtnNext">BtnNext</button>

Updated

According to @sh1rts's comment, you should also make sure that

Add a ClientIdMode="Static" to that definition, without this it won't have that ID on the actual page

Answer 2

Correct Syntax

$('#TxtPTypeValue').val()

When used to return value:

This method returns the value of the value attribute of the FIRST matched element.

When used to set value:

This method sets the value of the value attribute for ALL matched elements.

Source of information here

Answer 3

Val is a function, so you have to call it like this val() .

Try the below code.

 function TransactionType() { var PType = $("#TxtPTypeValue").val(); alert(PType); if (PType == "CC") { // SubmitCCTransaction(); } else if (PType == "EC") { // SubmitECheckTransaction(); }; };

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <textarea id="TxtPTypeValue"></textarea> <button onclick="TransactionType()">Print Value</button>

Answer 4

 $(document).ready(function(){ $('input:text').val(); });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <input type="text" id="txtvalue" value="425656">

Answer 5

如果要使用服务器端控件的值，则必须传递控件的客户端 ID，例如：

$("#<%=TxtPTypeValue.ClientId%>").val();