Delphi DLL

Call a JavaScript Function Passing an Array Argument

See more JavaScript Examples

Demonstrates how to call a JavaScript function with an argument that is an array. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Js, StringBuilder, JsonArray, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
sbScript: HCkStringBuilder;
js: HCkJs;
result: HCkJsonObject;
funcCall: HCkJsonObject;
argsArray: HCkJsonArray;
arg: HCkJsonArray;
sbOut: HCkStringBuilder;

begin
success := False;

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

// function calculateTotal(numbers) {
//   console.log(numbers);
//   let total = 0;
//   
//   // Loop through every number in the array
//   for (const num of numbers) {
//     console.log(num);
//     total += num;
//   }
//   
//   return total;
// }

sbScript := CkStringBuilder_Create();
success := CkStringBuilder_LoadFile(sbScript,'js_function_array_arg.js','utf-8');
if (success = False) then
  begin
    Memo1.Lines.Add(CkStringBuilder__lastErrorText(sbScript));
    Exit;
  end;

js := CkJs_Create();

result := CkJsonObject_Create();
CkJsonObject_putEmitCompact(result,False);

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

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

// ------------------------------------------------------------------------------
// Call the function calculateTotal(numbers)

funcCall := CkJsonObject_Create();
CkJsonObject_putEmitCompact(funcCall,False);

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

CkJsonObject_UpdateString(funcCall,'name','calculateTotal');

// Create the arguments array.
argsArray := CkJsonArray_Create();

// The 1st argument in the arguments array is itself an array.
// Passing -1 indicates to append to the array.
arg := CkJsonArray_Create();
CkJsonArray_AddArrayAt2(argsArray,-1,arg);

// Fill in the values for the 1st argument.
CkJsonArray_AddNumberAt(arg,-1,'10.50');
CkJsonArray_AddNumberAt(arg,-1,'20.00');
CkJsonArray_AddNumberAt(arg,-1,'5.25');

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

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

// The funcCall is as follows.  Notice that the 1st (and only) argument is an array.

// {
//   "name": "calculateTotal",
//   "args": [
//     [
//       10.50,
//       20.00,
//       5.25
//     ]
//   ]
// }

success := CkJs_CallFunction(js,funcCall,result);
if (success = False) then
  begin
    // Examine the result for an exception.
    Memo1.Lines.Add(CkJsonObject__emit(result));

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

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

// Result:
// {
//   "type": "double",
//   "value": 35.75
// }

// The function also emitted text to the console.

sbOut := CkStringBuilder_Create();
CkJs_ConsoleOutputSb(js,sbOut);
Memo1.Lines.Add(CkStringBuilder__getAsString(sbOut));

// Output:
// 10.5,20,5.25
// 10.5
// 20
// 5.25

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

CkJsonObject_Clear(funcCall);
CkJsonObject_UpdateString(funcCall,'name','calculateTotal');
CkJsonObject_UpdateNumber(funcCall,'args[0][0]','10.50');
CkJsonObject_UpdateNumber(funcCall,'args[0][1]','20.00');
CkJsonObject_UpdateNumber(funcCall,'args[0][2]','5.25');
Memo1.Lines.Add(CkJsonObject__emit(funcCall));

CkStringBuilder_Dispose(sbScript);
CkJs_Dispose(js);
CkJsonObject_Dispose(result);
CkJsonObject_Dispose(funcCall);
CkJsonArray_Dispose(argsArray);
CkJsonArray_Dispose(arg);
CkStringBuilder_Dispose(sbOut);

end;