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