VB.NET

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