VB.NET

Call a JavaScript Function Returning an Array

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

Dim success As Boolean = False

' ----------------------------------------------------------------------------------
' The Javascript functions called in this example are shown at the bottom of this page.
' -----------------------------------------------------------------------------------

Dim sbScript As New Chilkat.StringBuilder
success = sbScript.LoadFile("js_function_returning_array.js","utf-8")
If (success = False) Then
    Debug.WriteLine(sbScript.LastErrorText)
    Exit Sub
End If


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 each function

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.

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

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": "array",
'   "value": [
'     "Monday",
'     "Tuesday",
'     "Wednesday",
'     "Thursday",
'     "Friday"
'   ]
' }

' Access each array value..
Dim count As Integer = result.SizeOfArray("value")
Dim i As Integer = 0
While i < count
    result.I = i
    Debug.WriteLine(result.StringOf("value[i]"))
    i = i + 1
End While

' ------------------------------------------------------------------------------
' Call the getRange(start,end) function

funcCall.Clear()
funcCall.UpdateString("name","getRange")
funcCall.UpdateInt("args[0]",14)
funcCall.UpdateInt("args[1]",21)
success = js.CallFunction(funcCall,result)
Debug.WriteLine(result.Emit())

' Output:
' {
'   "type": "array",
'   "value": [
'     14,
'     15,
'     16,
'     17,
'     18,
'     19,
'     20,
'     21
'   ]
' }

count = result.SizeOfArray("value")
i = 0
While i < count
    result.I = i
    Debug.WriteLine(result.IntOf("value[i]"))
    i = i + 1
End While

' ------------------------------------------------------------------------------
' Call the getEmployees() function

funcCall.Clear()
funcCall.UpdateString("name","getEmployees")
success = js.CallFunction(funcCall,result)
Debug.WriteLine(result.Emit())

' Output:
' {
'   "type": "array",
'   "value": [
'     {
'       "id": 101,
'       "name": "Alice",
'       "role": "Dev"
'     },
'     {
'       "id": 102,
'       "name": "Bob",
'       "role": "Manager"
'     }
'   ]
' }

count = result.SizeOfArray("value")
i = 0
While i < count
    result.I = i
    Debug.WriteLine("name: " & result.StringOf("value[i].name"))
    Debug.WriteLine("role: " & result.StringOf("value[i].role"))
    Debug.WriteLine("id: " & result.IntOf("value[i].id"))
    Debug.WriteLine("")
    i = i + 1
End While