(Delphi ActiveX) JavaScript console using Callbacks

See more JavaScript Examples

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.jsProgressInfo(ASender: TObject;  const name: WideString; const value: WideString);
begin
    // TThread.Synchronize provides safety for callbacks that occur in a background thread..
    TThread.Synchronize(nil, procedure begin
      Memo1.Lines.Add(name + ': ' + value);
      end);
end;


procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
sbScript: TChilkatStringBuilder;
js: TChilkatJs;
result: TChilkatJsonObject;

begin
    success := 0;

    // This example demonstrates using the built-in console object.
    // The Javascript run in this example is shown below.

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

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

    // Run the JavaScript
    // Results (not console output) go to result.
    // Note: 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 console.log which does not calculate a value. Therefore, it returns undefined.
    success := js.Eval(sbScript.ControlInterface,result.ControlInterface);
    if (success = 0) then
      begin
        Memo1.Lines.Add(sbScript.LastErrorText);
        Exit;
      end;

    // We can look at the result, which is "undefined", which is normal and expected.
    Memo1.Lines.Add(result.Emit());
    // The result JSON is: {"type":"undefined","value":"undefined"}

    // The console output is received using ProgressInfo callbacks.
    // The output is:

    // log: Hello World, 248, 12.05
    // 
    // error: foo:bar baz
    // 
    // warn: 1 2 3
    // 
    // log: %% %s
    // 
    // log: myApp: {
    //   "appName": "Example",
    //   "version": 1,
    //   "isDebug": true,
    //   "supportedTypes": [
    //     "string",
    //     "number",
    //     "object"
    //   ],
    //   "settings": {
    //     "maxWidgets": 1024,
    //     "allowIO": true
    //   }
    // }
    // 
    // log: App: myApp (Version 1)
    // 
    // {"type":"undefined","value":"undefined"}
end;

// Chilkat Js console emits CRLF line endings on Windows, and LF line endings on non-Windows.

console.log("Hello %s, %d, %f", "World", 248, 12.05);
// Output: Hello World, 248, 12.05

// If there are more arguments than the number of specifiers, the extra arguments are output, separated by spaces:
console.error('%s:%s', 'foo', 'bar', 'baz');
// Output: foo:bar baz

// If the first argument does not contain a valid format specifier, outputs a string that is the concatenation of all arguments separated by spaces:
console.warn(1,2,3);
// Output: 1 2 3

//If only one argument is passed, it is returned as it is without any formatting:
console.log("%% %s");
// Output: %% %s

const myApp = {
    appName: "Example",
    version: 1.0,
    isDebug: true,
    supportedTypes: ["string", "number", "object"],
    settings: {
       "maxWidgets": 1024,
        allowIO: true
    }
};

// %O: Emits the same as JSON.stringify(myConfig, null, 2)
console.log("myApp: %O", myApp);
// Output:
// myApp: {
//   "appName": "Example",
//   "version": 1,
//   "isDebug": true,
//   "supportedTypes": [
//     "string",
//     "number",
//     "object"
//   ],
//   "settings": {
//     "maxWidgets": 1024,
//     "allowIO": true
//   }
// }

console.log("App: %s (Version %d)", myApp.appName, myApp.version);
// Output: App: Example (Version 1)