when click on empty asp:textbox I want to set the visibility of a asp:label to false immediately

Question

when click on empty asp:textbox I want to set the visibility of a asp:label to false immediately i set some label's to validation check when the textbox is empty , the label become visible but when text changed or clicked on textbox to edit it is not invisibled please help me

code :

 protected void Button1_Click(object sender, EventArgs e)
{
    if (TextBox1.Text == "")
        Label1.Visible = true;

}
protected void TextBox1_TextChanged(object sender, EventArgs e)
{
    Label1.Visible = false;

}

Answer 1

Make sure you have kept AutoPostBack="true" on TextBox1

protected void Button1_Click(object sender, EventArgs e)
{
        if (TextBox1.Text == "")
            Label1.Visible = true;

}
protected void TextBox1_TextChanged(object sender, EventArgs e)
{
        if(TextBox1.Text != string.empty)
        {
            Label1.Visible = false;
        }

}

But there are other efficient ways to validate the same. eg. ASP Validators, JQuery Validators

Answer 2

You can hide your label immediately with JQuery (without page reload). You textbox and label have ID and you can get them using ClientID property in asp.net 4.

$(document).ready(function(){
    var textbox = $('#<%=textboxId.ClientID%>');
    var label = $('#<%=labelId.ClientID%>');

    textbox.click(function(){
        if(textbox.val().length == 0){
            label.hide();
        }
    });
}); 

Answer 3

Try to use jquery here.

Here the label visibility will change according to textbox value changes.

Code

$(function () {
    $('#<%= txtbox1.ClientID%>').on('change keyup paste', function () {
        if ($('#<%= txtbox1.ClientID%>').val().length == 0) {
            $('#<%= lblTest.ClientID%>').css("visibility", "hidden");
        }
        else {
            $('#<%= lblTest.ClientID%>').css("visibility", "visible");
        }
    });
});