VB.NET

JavaScript console using Callbacks

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Demonstrates console output using Chilkat JavaScript with callbacks. VB.NET

' ProgressInfo callback method.
Private Sub js_OnProgressInfo(sender As Object, args As Chilkat.ProgressInfoEventArgs) Handles js.OnProgressInfo

    Dim name As String = args.Name
    Dim value As String = args.Value
        Debug.WriteLine(name & ": " & value)
End Sub

private Sub ChilkatExample()

    Dim success As Boolean = False

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



    '  Load the JavaScript from a file.
    Dim sbScript As New Chilkat.StringBuilder
    success = sbScript.LoadFile("qa_data/js_tests/test_console.js","utf-8")
    If (success = False) Then
        Debug.WriteLine(sbScript.LastErrorText)
        Exit Sub
    End If


    Dim WithEvents js As New Chilkat.Js
    Dim result As New Chilkat.JsonObject

    '  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,result)
    If (success = False) Then
        Debug.WriteLine(sbScript.LastErrorText)
        Exit Sub
    End If


    '  We can look at the result, which is "undefined", which is normal and expected.
    Debug.WriteLine(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 Sub

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)