Javascript alert with "Sweet Alert" called from VB.Net code behind

Question

In my application I am firing javascript alerts with Sweet Alerts from VB.Net code behind, on various page loads and events. I can get the basic alert firing no problem as shown below:

Dim script As String = String.Format("swal('Welcome , " + Username + "');")

ScriptManager.RegisterClientScriptBlock(Page, GetType(System.Web.UI.Page), "redirect", script, True)

There are other alerts available, which involve adding an object inside the quotes of the alert:

swal({   
         title: "Sweet!",   
         text: "Here's a custom image.",   
         imageUrl: "images/thumbs-up.jpg" 
    });

So my question is, when i want to use this in my code behind, im having trouble knowing where to add quotes in the right places, the object seems to cause a syntax error

Dim script As String = String.Formatswal({   title: "Sweet!",   text: "Here's a custom image.",   imageUrl: "images/thumbs-up.jpg" });

ScriptManager.RegisterClientScriptBlock(Page, GetType(System.Web.UI.Page), "redirect", script, True)

modal_dialog · Accepted Answer · 2015-11-07 20:57:50Z

1

From the VB.NET/server-side perspective, none of the JavaScript is code, it's just a string to be emitted in the response. So to start, everything given to String.Format() must be in a VB.NET string, with double quotes:

Dim script As String = "just a string to VB";

From there on, you are just trying to get the contents of the string to be exactly what's need for valid JavaScript on the client. There are two ways to handle:

Anywhere inside the string where you need the quote character ("), use two-quotes instead (""):

Dim script As String = "<script>swal({title:""Sweet!"", text:""Here's a custom image."", imageUrl:""images/thumbs-up.jpg""});</script>"

OR, second way: JavaScript allows using EITHER single quote (') or double-quote ("). Since VB.NET doesn't consider single-quote a special character, just replace all your JavaScript double-quotes with single quotes:

Dim script As String = "<script>swal({title:'Sweet!', text:'Here's a custom image.', imageUrl:'images/thumbs-up.jpg'});</script>"

Lastly, String.Format is used to easily insert variable values into your string. It uses {0} {1} {2} etc. as substitution values. Then you pass in the variables as additional params. That's why you have to escape the {} chars. Here's an example:

Dim script As String = String.Format("<script>swal({{title:'{0}', text:'{1}', imageUrl:'{2}'}});</script>", strTitle, strText, strImageUrl)

edited Nov 7, 2015 at 20:57

answered Nov 7, 2015 at 20:40

modal_dialog

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1 Comment

Johnn5er Over a year ago

Thanks very much for your help but i have tried both these techniques and both have a compile error "Input string was not in a correct format."

haraman · Accepted Answer · 2015-11-07 21:14:51Z

1

Its just a simple case of string concatenation containing quotes

Dim script As String = "<script type='text/javascript'>swal({   title: ""Sweet!"",   text: ""Here's a custom image."",   imageUrl: ""images/thumbs-up.jpg"" });</script>"

You can include double quotes in a string by escaping them with another double quote

edited Nov 7, 2015 at 21:14

answered Nov 7, 2015 at 20:37

haraman

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8 Comments

Johnn5er Over a year ago

Thanks for your response, but i tried that, it gve me a compile error:System.FormatException: Input string was not in a correct format.

haraman Over a year ago

Try using it without String.Format. Just a simple string assignment.

modal_dialog Over a year ago

Yes, get rid of String.Format because the {} are used by it. You'd have to escape with {{ and }}. Just do the simple string assignment. I'll edit my answer to reflect that too.

Johnn5er Over a year ago

Thanks for the info, but it seems ScriptManager.RegisterClientScriptBlock(Page, GetType(System.Web.UI.Page), "redirect", script, True) wont work without it

modal_dialog Over a year ago

@Johnn5er, you're script block needs to be wrapped in the <script> tags. It does not add them for you. That may be part of your problem. I'll edit my answer.

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