Delphi ActiveX Requires Chilkat v11.4.0+

Call a JavaScript Function Passing an Object Argument

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Demonstrates how to call a JavaScript function with an argument that is an object. Delphi ActiveX

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());