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

JavaScript

function getDays() {
    return ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"];
}

function getRange(start, end) {
    var arr = [];
    for (var i = start; i <= end; i++) {
        arr.push(i);
    }
    return arr;
}
// Usage: getRange(1, 5) -> [1, 2, 3, 4, 5]

function getEmployees() {
    return [
        { id: 101, name: "Alice", role: "Dev" },
        { id: 102, name: "Bob", role: "Manager" }
    ];
}