(Delphi ActiveX) Call a JavaScript Function Passing an Object Argument

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Note: This example requires Chilkat v11.4.0 or greater.

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
sbScript: TChilkatStringBuilder;
js: TChilkatJs;
result: TChilkatJsonObject;
funcCall: TChilkatJsonObject;
arg: TChilkatJsonObject;
argsArray: TChilkatJsonArray;
sbOut: TChilkatStringBuilder;

begin
success := 0;

// This is the JavaScript function we'll call:

// function describeCar(car) {
// 	console.log(`This is a ${car.year} ${car.make} ${car.model}.`);
// }

sbScript := TChilkatStringBuilder.Create(Self);
sbScript.Append('function describeCar(car) { console.log(`This is a ${car.year} ${car.make} ${car.model}.`); }');

js := TChilkatJs.Create(Self);

result := TChilkatJsonObject.Create(Self);
result.EmitCompact := 0;

// Call Eval to add the function to the context's global object
success := js.Eval(sbScript.ControlInterface,result.ControlInterface);
if (success = 0) then
  begin
    // Examine the result for an exception.
    Memo1.Lines.Add(result.Emit());

    // Also examine the LastErrorText.
    Memo1.Lines.Add(js.LastErrorText);
    Exit;
  end;

// ------------------------------------------------------------------------------
// Call the function describeCar(car)

funcCall := TChilkatJsonObject.Create(Self);
funcCall.EmitCompact := 0;

// Create JSON specifying the function name and arguments
// In this case, there is only 1 argument, and it is an object.

// {
//   "name": "describeCar",
//   "args": [
//     {
//       "make": "Toyota",
//       "model": "Corolla",
//       "year": 2022
//     }
//   ]
// }

funcCall.UpdateString('name','describeCar');

// Create the JSON object that is the argument.
arg := TChilkatJsonObject.Create(Self);
arg.UpdateString('make','Toyota');
arg.UpdateString('model','Corolla');
arg.UpdateInt('year',2022);

// Create the arguments array.
argsArray := TChilkatJsonArray.Create(Self);
argsArray.AddObjectCopyAt(0,arg.ControlInterface);

// Add the "args" array to the funcCall.
funcCall.AppendArrayCopy('args',argsArray.ControlInterface);

Memo1.Lines.Add(funcCall.Emit());

success := js.CallFunction(funcCall.ControlInterface,result.ControlInterface);
if (success = 0) then
  begin
    // Examine the result for an exception.
    Memo1.Lines.Add(result.Emit());

    // Also examine the LastErrorText.
    Memo1.Lines.Add(js.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add(result.Emit());

// The describeCar JavaScript function returns nothing. 
// Therefore, the result is "undefined".

// {
//   "type": "undefined",
//   "value": "undefined"
// }

// However, the function emitted text to the console.

sbOut := TChilkatStringBuilder.Create(Self);
js.ConsoleOutputSb(sbOut.ControlInterface);
Memo1.Lines.Add(sbOut.GetAsString());

// Output:
// This is a 2022 Toyota Corolla.

// -----------------------------------------------------------
// Note: If the object argument is simple, this is an alternative
// and simpler way of creating the funcCall:

funcCall.Clear();
funcCall.UpdateString('name','describeCar');
funcCall.UpdateString('args[0].make','Toyota');
funcCall.UpdateString('args[0].model','Corolla');
funcCall.UpdateInt('args[0].year',2022);
Memo1.Lines.Add(funcCall.Emit());
end;