Dart Requires Chilkat v11.4.0+

JavaScript console using Callbacks

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Demonstrates console output using Chilkat JavaScript with callbacks. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example demonstrates using the built-in console object.
  // The Javascript run in this example is shown below.

  // Load the JavaScript from a file.
  final sbScript = CkStringBuilder();
  try {
    sbScript.loadFile('qa_data/js_tests/test_console.js', 'utf-8');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final js = CkJs();

  js.onProgressInfo = (name, value) {
    print('$name: $value');
  };
  final result = CkJsonObject();

  // 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.
  try {
    js.eval(sbScript, result);
  } on ChilkatException {
    print(sbScript.lastErrorText);
    return;
  }

  // We can look at the result, which is "undefined", which is normal and expected.
  print(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"}
}

JavaScript

// 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)