Check textbox is changed or not using javascript C#.net

Introduction:

In my previous article I am explained about the Check uncheck all checkboxes in grid view using jquery . In this article I am going to explain about how to check whether the textbox value is changed or not using javascript and c#.net.

Explanation:

While working in a project I came to the following situation. There is a textbox in my webpage and i want to submit form only if the textbox's value has changed else i want to show some validation message. For this I have written code both in C#.net and javascript. 

I have two textboxes in form one for explain c# validation and another one for explaining the javascript validation. Below is the aspx code.

<table>

<tr>

<td>

    <asp:TextBox ID="txtName" runat="server" Text="type your name here.."></asp:TextBox>

</td>

<td>

    <asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_click" />

</td>

<td>

    <asp:Label ID="lblmsg" runat="server" Text=""></asp:Label>

</td>

</tr>

<tr>

<td>

    <asp:TextBox ID="txtDescription" runat="server" Text="type description here.."></asp:TextBox>

</td>

<td>

    <asp:Button ID="Button1" runat="server" Text="Submit" OnClientClick="return validate();" />

</td>

</tr>

</table>

In code behind I am using the viewstate to store the default valuew of the textbox. On button submit I am checking whether the current value of textbox and view state value is equal. If it is equal I am returning the error message as  textbox value is not changed. After that I used return statement. return Statement is used to terminate the to come out of the function. Below is the cs code.

protected void Page_Load(object sender, EventArgs e)

{

    if (!IsPostBack)

    {

        ViewState["txtValue"] = txtName.Text;

    }

}

protected void btnSubmit_click(object sender, EventArgs e)

{

    if (txtName.Text == ViewState["txtValue"].ToString())

    {

        lblmsg.Text = "Text box value is not changed..";

  return;

    }

    else

        lblmsg.Text = "Text box value is changed..";

}

Whereas in javascript to check whether the textbox value is changed or not I wrote validate function. This function will declare the textbox default value. After that it will get the current value of the textbox. After that it wil check whether the both the values are equal. Accordingly it will alert the user.return false;Is used to avoid the form submission.Below is the javascript code.

<script type="text/javascript">

    function validate() {

        var defaultval = "type description here..";

        var idval = document.getElementById('<%=txtDescription.ClientID %>').value

        if (idval == defaultval) {

            alert("Textbox value is not changed...");

            return false;

        }

        else {

            alert("Textbox value is changed...");

            return false;

        }

    }   

</script>

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