Develop Reference

How to pass a value from JavaScript to code behind?

I want get a value from js to code behind but the value is always an empty string.
I tried to pass the value from js to a label with runat="server" specified but in vain.
html:
<input type="hidden" runat="server" id="Val1"/>
js:
document.getElementById("Val1").value = MyFunction();
function MyFunction()
{
var value = "111";
}
code behind:
protected void sss(object sender, EventArgs e)
{
string aa = Val1.Value;
}

You could also use the Session to return your data.
In js:
sessionStorage.setItem('Val1', '111');
In code behind:
int Val1 = Convert.ToInt32(Session["Val1"]);

Use this
var val = document.getElementById('<%=val1.Client ID%>');
val.value= "111';
In your cs use val1.value

cannot get the newest button name in C#

my asp project has a asp button which named 'Save'. However, i need to change it to 'Update' in jQuery to do other thing in one button.
The problem is the C# onclick code is still read it as Save..
Code:
//Main
<asp:Button ID="btnSubmit" runat="server" Text="Save" />
//JQuery
$("#<%=btnSubmit.ClientID %>").val("Update");
//C#
var button = sender as Button;
var buttonName = button.Text; //Save
Update1
Question is:
I need to change the button name in JQuery
$("#<%=btnChangeName.ClientID %>").click({
$("#<%=btnSubmit.ClientID %>").val("Update"); //Change Save to Update
});
Then use it in C#:
protected void btnSubmit_Click(object sender, EventArgs e)
{
var button = sender as Button;
var buttonName = button.Text;
if (buttonName == "Save")
{//something}
else
{//something}
}

if you want to change the Name to Update1 in Jquery
try like this
$("#<%=btnSubmit.ClientID%>").val('Update');
Event you neeed to use is OnClientClick
Usage example
OnClientClick="onupd();return false;"
Update
Decalre a Hidden FIeld
<asp:HiddenField runat="server" ID="hdntest" Value="0" />
assign the button change value to update and assign it to the hidden field
not access that hidden value in your code behind.
you can assign Button value to Hidden Field like this
$("#<%=btnSubmit.ClientID %>").val("Update");
$("#<%=hdntest.ClientID%>").val($("#<%=btnSubmit.ClientID%>").attr("value"));

If you change the Button.Click value, then it will move to a different method onClick;
private void Form1_Load(object sender, EventArgs e)
{
Button b = new Button();
b.Name = "btnSubmit";// creating here for intellisense - you would create on your front-end
bool recordExists = true;
Button b1 = Controls.Find("btnSubmit", true)[0] as Button;
//the above is for winforms - you'd have to change for web form
b1.Text = recordExists ? "Update" : "Save";
b1.Click += doUpdateOrSave;
}
protected void doUpdateOrSave(object sender, EventArgs e)
{
Button b = sender as Button;
if (b.Text == "Save")
{
//save
}else
{
//update
}
}

Call Javascript Function From Server Side C#

I created a report that shows a list of manifests. The user can search through this list by the manifest number. When the code is running the search, I'm displaying a Gif:
But this Gif won't disappear once the search is finished. I can see the correct record is being displayed so the search is over, but the Gif stays on the screen.
The function is called when the search button is clicked.
<asp:Button runat="server" CssClass="btnSearch loading" ID="btnSearch" Text="Search" OnClick="btnSearch_Click" OnClientClick="ShowLoadingGif()" ToolTip="Search" />
<div id="dvLoading">
<table>
<tr>
<td id="tdLoadingSave"><img src="/images/loading.gif" alt="Loading..." title="Loading..." /></td>
</tr>
</table>
</div>
function ShowLoadingGif() {
closefiltermenu();
$("#tdLoadingSave").html($("#tdLoadingSave").html() + "<br/> Please wait, manifest list is loading");
$('#dvLoading').fadeIn("500");
}
function CloseLoadingGif() {
$('#dvLoading').fadeOut("500");
}
The search is then run from another function:
protected void Search()
{
string Field = ddlSearchBy.SelectedValue;
string SearchString = txtSearchBy.Text;
string[] SearchFields = null;
string[] SearchStrings = null;
if (!string.IsNullOrEmpty(SearchString) && Field != "null")
{
SearchFields = new string[] { Field };
SearchStrings = new string[] { SearchString };
}
List<lookupManifestAnalysis> main = lookupManifestAnalysis.SearchManifestItems(Company.Current.CompanyID,
SearchStrings,
SearchFields);
gvResults.DataSource = main;
gvResults.DataBind();
udpResults.Update();
ClientScript.RegisterStartupScript(GetType(), "Search", "CloseLoadingGif();", true);
}
But how do I stop the Gif displaying once the search is over?

ScriptManager.RegisterStartupScript(this, GetType(), "CloseLoadingGif","CloseLoadingGif();", true);
OR
If you are dealing with asp.net UpdatePanel and UpdateProgress, use the following code:
ScriptManager.RegisterStartupScript(myUpdatePanelID,myUpdatePanelID.GetType(),"CloseLoadingGif", "CloseLoadingGif();", true);

When you are executing your code in Server side ASP you should not use client side function for showing or hiding elements. Instead try using Ajax Controls from .Net.
You will need to use AJAX Progress control. Here have a look :
https://msdn.microsoft.com/en-us/library/bb386421.aspx

How to call javascript function from asp:textbox?

I am using textbox for searching items from data base and loading them in gridview and
i used custom paging on gridview to show only 25 records per page
and i found java script for searching records on client side as
script>
function filter2(phrase, _id) {
var words = phrase.value.toLowerCase().split(" ");
var table = document.getElementById(_id);
var ele;
for (var r = 1; r < table.rows.length; r++) {
ele = table.rows[r].innerHTML.replace(/<[^>]+>/g, "");
var displayStyle = 'none';
for (var i = 0; i < words.length; i++) {
if (ele.toLowerCase().indexOf(words[i]) >= 0)
displayStyle = '';
else {
displayStyle = 'none';
break;
}
}
table.rows[r].style.display = displayStyle;
}
}
</script>
and calling this as:
<input name="txtTerm" onkeyup="filter2(this, '<%=GridView1.ClientID %>')" placeholder="Search" type="text"/>
this function search record from activated page and obviously searching from whole database will be done on server side and i used asp textbox
but i need onkeyup="filter2(this, '<%=GridView1.ClientID %>')"event in my asp textbox e-g
<asp:TextBox ID="txtSearch" onkeyup="filter2(this, '<%=GridView1.ClientID %>')" placeholder="Search" runat="server" AutoPostBack="True" OnTextChanged="txtSearch_TextChanged" />
but asp didn't allow me to do that..
i need your help to achieve this.
thanks in advance.
EDIT:
I need both searching (client side, server side) in single textbox
because
client side allow searching from loaded page of gridview and
server side allow searching from database on clicking

You could add the client attribute of rendered input control via code behind:
protected void Page_Load(object sender, EventArgs e)
{
txtSearch.Attributes.Add("onkeyup", string.Format("filter2(this,'{0}')",GridView1.ClientID)");
}
EDIT:
After the right comment of #Lukas, we should say that the main problem was the use of <%=GridView1.ClientID %> inline expression inside the textbox webcontrol:
<%= %> will write the string directly to the response-stream, which happens after the server control is constructed, so will be rendered as string and not resolved.
For example:
<asp:Label runat="server" ID="label">test</asp:Label>
<asp:TextBox runat="server" ID="txt" Text="<%# label.ID %>" onkeyup="alert('<%: label.ID %>')"></asp:TextBox>
This is what we have in output:

How to enable asp:LinkButton on client side

I have asp:LinkButton, input Button defined as:
<asp:LinkButton ID="lnkViewPdf" runat="server" CssClass="icoMiniTest" ClientIDMode="Static" >View Office Pdf</asp:LinkButton>
<input id="Button2" type="button" value="TestEnable" onclick="TestEnable(document.getElementById('lnkViewPdf'));" />
the LinkButton is initially disabled in code-behind as:
if (!IsPostBack)
{
this.lnkViewPdf.Enabled = false;
}
and needs to be enabled when Button2 is clicked, so I am calling javascript function to enable the link as:
function TestEnable(lnkbutton) {
alert('TestEnable() called');
alert(lnkbutton.id);
lnkbutton.disabled = "";
//$("#lnkbutton").removeAttr('disabled'); //even this doesn't work
}
But I am not able to enable the linkbutton.
Am I missing something?
Thank you!
__________________________________________________
Anyone interested in solution to above problem:
In code-behind:
this.lnkViewPdf.Attributes["disabled"] = "disabled";
this.lnkViewPdf.Attributes["onclick "] = "return false";
.js:
function TestEnable(lnkbutton) {
$(lnkbutton).removeAttr('disabled');
lnkbutton.onclick = "";
}
NOTE: When setting lnkViewPdf.Enabled = false; LinkButton was being rendered as
<a id="lnkViewPdf" class="aspNetDisabled icoMiniTest">View Office Pdf</a>
see the style class aspNetDisabled, something added by ASP.Net
However setting disabled/onclick attributes from the codebehind as shown above, render Linkbutton as:
<a id="lnkViewPdf" class="icoMiniTest" disabled="disabled" onclick ="return false" href="javascript:__doPostBack('lnkViewPdf','')">View Office Pdf</a>
HTH.

Try now...
function TestEnable(lnkbutton) {
lnkbutton.disabled = "";
lnkbutton.onclick = "";
}

In the code behind, rather than disable by setting Enabled = false, set:
lnkViewPdf.Attributes["disabled"] = "disabled"
So your javascript function:
function TestEnable(lnkbutton) {
alert('TestEnable() called');
alert(lnkbutton.id);
lnkbutton.disabled = "";
}
Your markup:
<asp:LinkButton ID="lnkViewPdf" runat="server" CssClass="icoMiniTest" ClientIDMode="Static" >View Office Pdf</asp:LinkButton>
<input id="Button2" type="button" value="TestEnable" onclick="TestEnable(document.getElementById('<%= lnkViewPdf.ClientID %>')); return false;" />
And your code-behind:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
lnkViewPdf.Attributes["disabled"] = "disabled";
}

$("#<%=lnkViewPdf.ClientID %>").removeAttr("disabled");

You need to know the .Net constructed name in order to accomplish it. The easiest way is to have it set in the head of the page if you can:
<script language="javascript">
var lnkbuttonToEnableId = "<%= this.lnkViewPdf.ClientId %>";
function TestEnable() {
alert('TestEnable() called');
lnkbuttonToEnableId.disabled = false;
}
</script>
At any rate, the only way to get it to work is to pass the ClientId of lnkViewPdf to the function somehow.

try both of those:
<input id="Button2" type="button" value="TestEnable"
onclick="TestEnable(document.getElementById('<%= lnkViewPdf.ClientID %>'));" />
or
$("#<%= lnkViewPdf.ClientID %>").removeAttr('disabled');
UPDATE: Since you are disabling the LinkButton on server side .NET strips the href attribute from the <a> html element. What you should do to prevent the lost of that information is to disable the LinkButton on the client and then enable it when you need to. Also instead of disabling it all you need to do is remove the href attribute.
So first you need to retain the href and remove it so the <a> link become disabled:
$(document).ready(function () {
var $lnkViewPdf = $("#lnkViewPdf");
$lnkViewPdf.data("href", $lnkViewPdf.attr("href"));
$lnkViewPdf.removeAttr("href");
});
and the function that enables it:
function TestEnable(lnkViewPdfId) {
var $lnkViewPdf = $("#" + lnkViewPdfId);
$lnkViewPdf.attr("href", $lnkViewPdf.data("href"));
}

If you disable the LinkButton using:
if (!IsPostBack)
{
this.lnkViewPdf.Enabled = false;
}
Then the href attibute won't be displayed in the HTML. If you manually add the disabled attribute instead:
if (!IsPostBack)
{
lnkViewPdf.Attributes.Add("disabled", "disabled");
}
Then you're code will work just fine.
Oh!.. and one last thing: You need to set the PostBackUrl property for the LinkButton. You missed it in your example.