Delphi ActiveX

Eval JavaScript Returning Int

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Demonstrates getting the completion value of a JavaScript that returns an integer. Delphi ActiveX

var
success: Integer;
sbScript: TChilkatStringBuilder;
js: TChilkatJs;
result: TChilkatJsonObject;

begin
success := 0;

//  This example demonstrates getting the completion value of a script,
//  where the last evaluated expression is an integer.

//  The Javascript run in this example is shown below.

//  Load the JavaScript from a file.
sbScript := TChilkatStringBuilder.Create(Self);
success := sbScript.LoadFile('js_eval_return_int.js','utf-8');
if (success = 0) then
  begin
    Memo1.Lines.Add(sbScript.LastErrorText);
    Exit;
  end;

js := TChilkatJs.Create(Self);
result := TChilkatJsonObject.Create(Self);

//  Run the JavaScript
//  Eval returns the completion value of the script. This is generally the value of the last evaluated expression.
//  In this case, the last evaluated expression is an int.
success := js.Eval(sbScript.ControlInterface,result.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(sbScript.LastErrorText);
    Exit;
  end;

result.EmitCompact := 0;
Memo1.Lines.Add(result.Emit());

//  Output:

//  {
//    "type": "int",
//    "value": 42
//  }

JavaScript

const base = 10;
const multiplier = 4;
const offset = 2;

// The last line is a calculation resulting in an integer
// Returns 42.
(base * multiplier) + offset;