VB.NET Requires Chilkat v11.4.0+

Call a JavaScript Function Returning an Object

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Demonstrates how to call a JavaScript function that returns an object. VB.NET

Dim success As Boolean = False

'  This is the JavaScript function we'll call:

'  function getSettings() {
'      return {
'          theme: "dark",
'          notifications: true,
'          version: 1.0
'      };
'  }

Dim sbScript As New Chilkat.StringBuilder
sbScript.Append("function getSettings() {")
sbScript.Append("    return {")
sbScript.Append("        theme: ""dark"",")
sbScript.Append("        notifications: true,")
sbScript.Append("        version: 1.0")
sbScript.Append("    };")
sbScript.Append("}")

Dim js As New Chilkat.Js

Dim result As New Chilkat.JsonObject
result.EmitCompact = False

'  Call Eval to add the function to the context's global object
success = js.Eval(sbScript,result)
If (success = False) Then
    '  Examine the result for an exception.
    Debug.WriteLine(result.Emit())

    '  Also examine the LastErrorText.
    Debug.WriteLine(js.LastErrorText)
    Exit Sub
End If


'  ------------------------------------------------------------------------------
'  Call the function getSettings()

Dim funcCall As New Chilkat.JsonObject

'  Create JSON specifying the function name and arguments
'  The function has no arguments, so we only specify the name.

'  {
'    "name": "getSettings",
'  }

funcCall.UpdateString("name","getSettings")

success = js.CallFunction(funcCall,result)
If (success = False) Then
    '  Examine the result for an exception.
    Debug.WriteLine(result.Emit())

    '  Also examine the LastErrorText.
    Debug.WriteLine(js.LastErrorText)
    Exit Sub
End If


Debug.WriteLine(result.Emit())

'  Output:
'  {
'    "type": "object",
'    "value": {
'      "theme": "dark",
'      "notifications": true,
'      "version": 1
'    }
'  }

'  Examine the object's members
Debug.WriteLine("theme: " & result.StringOf("value.theme"))
Debug.WriteLine("notifications: " & result.BoolOf("value.notifications"))
Debug.WriteLine("version: " & result.IntOf("value.version"))

'  Output:
'  theme: dark
'  notifications: True
'  version: 1