Is it possible to call c# Method from js?

rovingwind · January 15

Is it possible to call c# Method from js?
I want to recall C# while js catch error like below.

Util.InvokeScript(false, "eval", @$"
try {{
  // do something         
}} catch (error) {{
  // call C# method         
}}
");

i2van · January 15

Maybe LIQPad is not a right tool for a job? Or HTML? For example, you can create an application using Avalonia, and use it in LINQPad.

Or you can return some error value from Util.InvokeScript and call C# code.

JoeAlbahari · January 16

If you just want to log the error, you could call external.log (see the sample 'Adding JavaScript - logging'). Or you could return a value to the caller when there's an exception.

rovingwind · January 16

I want to recall c# method by user's SweetAlert select dialog

string UrlSweetAlert2Js = "https://cdn.jsdelivr.net/npm/sweetalert2@11";
Util.HtmlHead.AddScriptFromUri(UrlSweetAlert2Js);

var js = """
Swal.fire({
  title: 'Do you want to save the changes ? ',         
  showDenyButton: true,
  showCancelButton: true,
  confirmButtonText: 'Save',
  denyButtonText: `Don't save`
}).then((result) => {
  /* Read more about isConfirmed, isDenied below */
  if (result.isConfirmed) {
    Swal.fire('Saved!', '', 'success');
    //call C# Method 1
  } else if (result.isDenied) {
    Swal.fire('Changes are not saved', '', 'info');
    //call C# Method 2
  }
});
""";

Util.InvokeScript(false, "eval", js);

i2van · January 16

In C# create invisible button with onClick handler.
In JavaScript set button text to the data you would like to pass to C# and initiate button click.

string UrlSweetAlert2Js = "https://cdn.jsdelivr.net/npm/sweetalert2@11";
Util.HtmlHead.AddScriptFromUri(UrlSweetAlert2Js);

// Create button for receiving callback fron JavaScript.
var callbackButton = new LINQPad.Controls.Button ("", onClick: btn => btn.Text.Dump())
{
  Visible = false
}.Dump();

var js = @$"
Swal.fire({{
  title: 'Do you want to save the changes ? ',
  showDenyButton: true,
  showCancelButton: true,
  confirmButtonText: 'Save',
  denyButtonText: `Don't save`
}}).then((result) => {{
  // Get callback button ID.
  let b = document.getElementById('{callbackButton.HtmlElement.ID}');
  if (result.isConfirmed) {{
    Swal.fire('Saved!', '', 'success');
    // Update button text.
    b.textContent = '{nameof(Saved.Yes)}';
  }} else if (result.isDenied) {{
    Swal.fire('Changes are not saved', '', 'info');
    // Update button text.
    b.textContent = '{nameof(Saved.No)}';
  }} else {{
    // Update button text.
    b.textContent = '{nameof(Saved.Cancel)}';
  }}
  // Do callback back to C#.
  b.click();
}});
";

Util.InvokeScript(false, "eval", js);

enum Saved
{
  Yes,
  No,
  Cancel
}

rovingwind · January 17

@i2van said:
1. In C# create invisible button with onClick handler.
2. In JavaScript set button text to the data you would like to pass to C# and initiate button click.

string UrlSweetAlert2Js = "https://cdn.jsdelivr.net/npm/sweetalert2@11";
Util.HtmlHead.AddScriptFromUri(UrlSweetAlert2Js);

// Create button for receiving callback fron JavaScript.
var callbackButton = new LINQPad.Controls.Button ("", onClick: btn => btn.Text.Dump())
{
  Visible = false
}.Dump();

var js = @$"
Swal.fire({{
  title: 'Do you want to save the changes ? ',
  showDenyButton: true,
  showCancelButton: true,
  confirmButtonText: 'Save',
  denyButtonText: `Don't save`
}}).then((result) => {{
  // Get callback button ID.
  let b = document.getElementById('{callbackButton.HtmlElement.ID}');
  if (result.isConfirmed) {{
    Swal.fire('Saved!', '', 'success');
  // Update button text.
      b.textContent = '{nameof(Saved.Yes)}';
  }} else if (result.isDenied) {{
    Swal.fire('Changes are not saved', '', 'info');
  // Update button text.
      b.textContent = '{nameof(Saved.No)}';
  }} else {{
  // Update button text.
      b.textContent = '{nameof(Saved.Cancel)}';
  }}
  // Do callback back to C#.
  b.click();
}});
";

Util.InvokeScript(false, "eval", js);

enum Saved
{
  Yes,
  No,
  Cancel
}

Thanks, It works perfectly

i2van · January 17

This is a PoC, so for production use I'd wrap implementation details in the class. Nothing like this can be found in LINQPad examples...

Is it possible to call c# Method from js?

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