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Call javascript using asp:button

I am trying to call a javascript function stored in separate js file using below code from aspx file
<asp:Panel ID="constraintPanel" runat="server">
<div class="rightColumn">
<div class="parseButtonDiv">
<asp:Button ID="Button" runat="server" class="button" Text="Parse"
OnClick="DoParseExpression();"/>
</div>
</div>
</asp:Panel>
The on click call is not going through.
Looking for suggestions
Thanks

Use OnClientClick
<asp:Button ID="Button" runat="server" class="button" Text="Parse"
OnClick="DoParseExpression();" OnClientClick="JavaScriptMethod();"/>
Client method will invoke first then it'll go to the server.

You have to add simple change to your code as below.
<asp:Button ID="Button" runat="server" class="button" Text="Parse" OnClick="DoParseExpression()" OnClientClick="return JSMethod()"/>
You can add your js file as normal way in your html page.
After adding above change at first it call Java Script method and then trigger asp method according to js method response.
NOTE: If this doesn't work, show your js method, then I can give correct solution according to your purpose.

In your case the OnClick triggers a request to server. You need to use OnClientClick https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.button.onclientclick(v=vs.110).aspx

Unable to make ASP.NET control button fade out with JQuery

I have a simple enough problem: I have an ASP.NET control button and I want to make it fade out and then call some function (such as an alert) using JQuery. Here is what I have so far:
ASP Code for the Button:
<div id="begin">
<span id="startButtonSpan">
<asp:Button ID="startButton" class="startButton" runat="server" Text="Click Me!" OnClientClick="startButtonClick()"/>
</span>
</div>
JavaScript:
function startButtonClick()
{
$("#startButtonSpan > input").fadeOut(500, callAlert());
}
function callAlert()
{
alert("Made it here...");
}
When I click the button, the alert displays but the page does not even seem to try to perform the fadeOut. When I close the alert, the button is still there, staring at me.
Can anyone see any mistakes or does anyone have any suggestions on how I might be able to achieve the intended goal of fading out my button? Fadeout is really just my way of testing whether I can manipulate ASP controls using jQuery, so more than just the simple fadeOut, this is me trying to learn how to do that.
I tried a slightly more simple jQuery call using the code below, but it does not seem to work either:
ASP Portion:
<div id="begin">
<span id="startButtonSpan">
<asp:Button ID="startButton" class="startButton" runat="server" Text="Click Me!" OnClientClick="startButtonClick()"/>
</span>
</div>
<div id="jQueryTest" style="display:none;">
Block for testing jQuery.
<h1 id="testMessage">Child element for the ASP div.</h1>
</div>
Javascript Portion:
function startButtonClick()
{
$("#jQueryTest").css("display", "block");
$("#jQueryTest").show();
}
For this example, the text does display, but it immediately disappears again.
Any help or suggestions as to what I might be doing wrong would be greatly appreciated.

Use the class as a selector $('.startButton') instead of the ID since ASP.Net controls change their IDs dynamically when rendered by appending its Page & Control information.
$(".startButton").fadeOut(500, callAlert);
Or, if you're adamant about using the ID, here is another way to handling the selector,
$("#<%=startButton.ClientID %>")
Or, as Jacob suggested in his answer, you could ClientIDMode="Static", but this works only if your application is .Net 4.0 or above.
Also, use CssClass instead of class
<asp:Button ID="startButton" Csslass="startButton" runat="server" Text="Click Me!" />

The first example has 2 problems.
1. You should write
$("#startButton").fadeOut(500, callAlert);
and not
$("#startButton").fadeOut(500, callAlert());
2. For ASP.NET you must set ClientIDMode="Static" ortherwise asp.net will alter your id.
<asp:Button ID="startButton" ClientIDMode="Static" ... OnClientClick="startButtonClick()"/>

How about the fact that your code is fine (although other answers here should be considered) but your button is making a post back to the server and simply your browser does not have enough time to render the fade effect.
To test this, add a return false; to the OnClientClick property. This will of course cancel your action on the server but you will obtain the fade effect:
<asp: Button ... OnClientClick="startButtonClick();return false;"></asp:Button>
To work around this and still submit your request, you can try to use the ASP.NET __doPostBack method in JavaScript
ASP.NET:
<asp:Button ID="startButton" class="startButton" runat="server" Text="Click Me!" OnClientClick="startButtonClick(this);return false;"/>
JavaScript:
function startButtonClick(button)
{
$("#startButtonSpan > input").fadeOut(500, function(){__doPostBack(button.name, "")});
}
The __doPostBack method takes two arguments: the name of the control that is doing the postback and a postback argument that can be use to send more info on the server. In the case of the asp:Button, the name of the button should be sufficient to send the request without a problem.
Using this technique you will fade the button on the client and also trigger the action on the server. I cannot guarantee that this exact code will work (I don't have access to a dev environment right now) but you should get the idea.

If I could, I would like to provide another answer for those that use MasterPages and find that you can't always use $("#<%= SomeContentControl.ClientID %>") when working with Content controls.
What I do is set the MasterPage ID in my Init() like this:
protected void Page_Init( object sender, EventArgs e )
{
// this must be done in Page_Init or the controls
// will still use "ctl00_xxx", instead of "Mstr_xxx"
this.ID = "Mstr";
}
Then, you can do something like this with your jQuery:
var masterId = "Mstr",
$startButton = getContentControl("startButton"),
$message = $("#jQueryTest");
function getContentControl( ctrlId )
{
return $("#" + masterId + "_" + ctrlId);
}
function hideStartButton()
{
$startButton
.stop(true, true)
.fadeOut("slow", showMessage);
}
function showMessage()
{
$message
.stop(true, true)
.fadeIn("slow");
}
$startButton.on("click", hideStartButton);
Here is a jsFiddle that has the Mstr_ prefix already inserted as if ASP.NET rendered it.

OnClientClick event in In ASP.NET

I'm using ASP.NET to pass a value to a JavaScript function and, for some reason I haven't been able to determine, it isn't working when I try to pass in a value from another control. Instead, it acts like there is a syntax error and it just submits back to the main form.
Does anyone know why?
Example:
<asp:TextBox ID="txtToSay" runat="server" Text="Something"></asp:TextBox>
<asp:Button runat="server" ID="btnSaySomething1" Text="Say Something"
OnClientClick="saySomething(<%=txtToSay.Text%>);" /> <!-- doesn't work -->
<asp:Button runat="server" ID="btnSaySomething1" Text="Say Something"
OnClientClick="saySomething('<%=txtToSay.Text%>');" /> <!-- doesn't work -->
<asp:Button runat="server" ID="btnSaySomething2" Text="Say Something"
OnClientClick="saySomething('Something');" /> <!-- works -->
<script type="text/javascript">
function saySomething(txt){
alert(txt);
};
</script>
Additional Information:
Web Application running on .NET 4.0
Language: C#
Update:
After working with this a while, I've determined that you can't use <%%> tags in ASP controls. Additionally, if you're looking for dynamic evaluation of control values AVOID AVOID AVOID using <%=someControl.Text%> or similar constructs since they are only evaluated once a request is submitted to the server. If you need a static value from another control at runtime, simply set that value in the page load event or handle it another way in the code behind.

Javacript will search for variable name = txtToSay.Text in saySomething function call, Put quotes around it to make it string value
Change
OnClientClick="saySomething(<%=txtToSay.Text%>);"
To
OnClientClick="saySomething('<%=txtToSay.Text%>');"
You can get the txtToSay.Text without passing it this way
<script type="text/javascript">
function saySomething(txt){
alert(document.getElementById('<%=txtToSay.Text%>').value);
};
</script>

you need to put ' around your text in the saySomething() call.
Like this:
<asp:Button runat="server" ID="btnSaySomething1" Text="Say Something" OnClientClick="saySomething('<%=txtToSay.Text%>');" />
UPDATE
<%= %> won't work inside an asp.net control. Can you set it from the code-behind?
I.E
btnSaySomething1.OnClientClick = "Text to say"

Finding an asp:button and asp:textbox in Javascript

What I'm trying to do is get an asp:button to click. The only problem is that it is within a few tags.
Example:
<loginview>
<asp:login1>
<logintemplate>
//asp:textbox and asp:button are located here.
</loginview>
</asp:login>
</logintemplate>
So how would I get javascript to point to that location so that I can manipulate it. For example, get the button to click.

First, you need to figure out which template is being used, since you can only access the active one. (Anonymous or LoggedIn). Once you do that, use the FindControl method on the LoginView to find the ClientID of the element you need to reference.
For example:
<form runat="server">
<asp:LoginView runat="server" ID="LoginView">
<AnonymousTemplate>
<asp:Button ID="ASPButton" Text="Button" runat="server" />
</AnonymousTemplate>
</asp:LoginView>
</form>
<script type="text/javascript">
var el = document.getElementById('<%= LoginView.FindControl("ASPButton").ClientID %>');
</script>

Check out the jQuery framework: you can find controls by ID, and then call methods/properties on those controls.
http://jquery.com/

asp button and history back onclientclick

hi I have an asp button which is created using the following code:
<asp:Button ID="btnBack" OnClientClick='javascript:history.back()' runat="server" Text="back">
</asp:Button>
However, now the javascript doesn't work to go a history back. On the other hand, if I make an alert() it works...why. Why is it not working to go a history back?

Try with return false at end:
<asp:button id="btnBack" runat="server" text="Back"
OnClientClick="JavaScript: window.history.back(1); return false;"></asp:button>

Try:
parent.history.back();
Or
history.go(-1)

Had the same problem in DevExpress project. Using ASPxButton without initializing the property "AutoPostBack" will result in redirect to self page before any client-side function call.
Try AutoPostBack="false" for the button.