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

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);

JavaScript

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;
}