I have a button that, when an user clicks on it and some fields are not correct, a message will be displayed. I would like to make that validation with javascript(or maybe someday I will), but I have no idea how to make that. Currently when the user clicks the button, the onclick function on the server side wont be executed.
Just use <asp:Validator tags; there are a number of different types of validators such as required field validators regex validators, etc.
They will validate the data both in client side code as well as server side code (unless you disable the client side check, which you can do).
This is much easier than manually validating the content in javascript and also manually validating it in server side code.
Technically though, to answer your question, when you have an onclick javascript handler for a submit button the return value, as a boolean, indicates whether or not the form should be submitted, so you just need to return false if the data is not valid to not submit the form.
<asp:Button Text="Submit" OnClientClick="return Validate();" />
<script type="text/Javascript">
function Validate()
{
if(requiredFieldAIsMissing) return false;
return true;
}
</script>
How about:
<asp:Button ID="myButton" Text="Click Me!" OnClick="myButton_OnClick" OnClientClick="javascript:confirm('Really?')" />
The OnClientClick property emits the javascript (ahead of the javascript required to handle the postback), and if you return false from that event the rest of the event is cancelled and the postback will not fire.
I think something like below would help you to understand.
HTML:
<asp:textbox id="myText" runat="server" text="Hello" />
<asp:button id="myButton" runat="server" text="Click Me" OnClick="Server_Event" />
ON Page_Load:
//Add onclick with return here
myButton.Attributes.Add("onclick","return ButtonClicked()");
Javascript:
function ButtonClicked(){
var txt = document.getElementById("myText");
if(txt.value != "Hello"){
alert("It is not Hello, I am NOT posting back!");
return false;
} else {
alert("It is Hello, I am posting back!");
return true;
}
}
Related
I have an asp:button called "Delete" and what I want to do is have a JavaScript confirm popup with the options "Yes" and "No". If "Yes" then delete a record from a SQL DB else if "No" then nothing should happen.
<asp:Button runat="server" ID="btnDelete" Text="Delete"
OnClientClick="if(confirm('Delete?'))alert('You chose yes!');else alert('You chose no!')"
OnClick="btnDelete_Click" />
btnDelete_Click contains SQL delete logic.
The problem I am having is that the OnClick method always gets executed. Whether you pick "Yes" or "No" from the JavaScript popup the record gets deleted regardless. It seems to always cause a postback.
Can I somehow get the "Yes" or "No" result into my code behind so I can actually do a simple "if" statement for the delete logic?
Try this, on your javascript do this
var result = Confirm("Are you sure . . . . ");
if(result)
return true;
else
return false;
what it does is if it's true, it should postback your code, else it'd cancel your click.
That should be:
<asp:Button runat="server" ID="btnDeleteSite" Text="Delete" OnClientClick="return confirm('Format Delete?');" OnClick="btnDeleteSite_Click" />
You should ideally put JS event handlers in the script tag, and call them from your OnClientClick event in the button definition. Like so:
<script type="text/javascript">
function ConfirmDelete() {
return confirm("Delete?");
}
</script>
And then in your button's OnClientClick event, you do this:
OnClientClick="return ConfirmDelete()"
This keeps your markup clean and readable, and will also prevent the postback from happening if the user chooses 'No'.
Try with this
<asp:Button runat="server" ID="btnDelete" Text="Delete" OnClientClick="if(confirm('Delete?')){return true;}else {return false;} OnClick="btnDelete_Click" />
When you are using OnClientClick event with JS confirm dialog box at that time you need to return true or false. If it will return True then OnClick(Server side) event will fire otherwise it will not.
my button on server works on alertMsg() how ever doesnt work on playSelected()
my button on Html works on playSelected() and alertMsg()
anyone can figure out for me why?
javascript
function playSelected() {
var a = "Video/" + document.getElementById("TextBox2").value + ".flv";
jwplayer("mediaplayer").setup({
flashplayer: "jwplayer/player.swf",
file: a,
image: "jwplayer/preview.jpg"
});
}
function alertMsg() {
alert("testing123");
}
button in html
input type="button" runat="server" value="Click me!" onclick='playSelected()'
button in server
asp:Button ID="Button2" runat="server" text="call javascript" OnClientClick="playSelected(); return true;" UseSubmitBehaviour="false"
<asp:Button runat="server"
OnClientClick='playSelected(); return true;'
UseSubmitBehaviour="false" />
Make sure your java script is allowed on the clietn browser. Also do postbacks logic in your page_load event. I would rather create the Button on overriden CreateChildControls method of the page, and on overriden OnPreRender wireup my java script and register the script with ClientScriptManager method RegisterStartupScript. So that you can have nice page life cycle control.
I working on an ASP.Net C# application, I wanted to create a Button Control, when user click on the button, a JavaScript confirm popup, then get the Boolean value from the user (Yes/No) to perform further actions in the button onClick event.
my current approach was added OnClientClick and OnClick event in the button, where OnClientClick trigger JavaScript function and the (Yes/No) value is store into HiddenField Control to make use during OnClick event.
It is something like the following code fragments:
function CreatePopup(){
var value = confirm("Do you confirm?");
var hdn1 = document.getElementById('hdn1');
hdn1.Value = value;
}
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" OnClientClick="CreatePopup()"/>
<asp:HiddenField ID="hdn1" runat="server" />
Is there any better approach in order to do this? thank you in advanced.
Change your CreatePopup() function to return a boolean:
function CreatePopup()
{
return confirm("Do you confirm?");
}
And then ensure you return that from the OnClientClick() in the button:
<asp:Button ... OnClientClick="return CreatePopup();" />
Using that method, the OnClick() method will only fire if the OnClientClick() method returns true.
Why do you want to store the value of the JavaScript confirmation in the hidden field? Just simply return false in your JavaScript function when the confirm value is 'no' , to prevent the form from submitting. When cnfirm value is yes, return true to allow the form to be submitted. In your code behind in the button_click method you don't have to check what happened in your JavaScript confirm, since form will never be submitted if the user said no.
I've the Javascript code to do a confirmation before deletion of some records
function confirmDelete()
{
if(confirm('Delete all?'))
{
return true;
}
else
{
return false;
}
}
I've the button code here
<asp:Button ID="btnDelete" runat="server" onClientClick="return confirmDelete();" onClick="btnDelete_click" />
If i've the button outside an update panel (basically i'm using RadAjaxPanel by Telerik) it is working fine. But when the button is inside an ajax panel, even if i click OK for deleting the records the server side code is not called.
Any ideas?
Your code is being prepended to the click handler that posts the action back to the server. You need to check if your result returns true/false then optionally continue executing the server-generated code.
<asp:Button ID="btnDelete" runat="server"
onClientClick="if (!confirmDelete()) { return false; }"
onClick="btnDelete_click" />
This will result in client-side HTML like
<input type="submit" id="btnDelete"
onclick="if (!confirmDelete()) { return false; } __DoPostBack...
allowing the server-generated code to be executed (i.e., no return is evaluated unless the confirmation fails).
OnclientClick of a button I hide a panel client side. I only want to hide it however if all input is valid. Is this possible in Javascript?
You can use the Page_IsValid property, it allows you to check whether the entire form is valid. You must call the Page_ClientValidate function before checking the value of Page_IsValid. This function is responsible for setting the value of the Page_IsValid property.
<asp:Panel ID="pnl" runat="server">
<asp:Button ID="btn" runat="server" Text="Click" OnClientClick="return Validate();" CausesValidation="false" />
<script type="text/javascript">
function Validate()
{
if (typeof(Page_ClientValidate) == 'function')
Page_ClientValidate();
var panel = document.getElementById('pnl');
if(Page_IsValid)
panel.style.display = 'none';
else
panel.style.display = 'block';
return false;
}
</script>
You would have to call the page validation functions manually. You can call the Page_ClientValidate(validationGroup) function to check a specific group. For a complete reference, you can check out the WebUIValidation.js file that is output by .NET 1.1.