Xojo Plugin

Call a JavaScript Function Returning an Integer

See more JavaScript Examples

Demonstrates how to call a JavaScript function that returns an integer. Xojo Plugin

Dim success As Boolean
success = False

// ----------------------------------------------------------------------------------
// The Javascript function called in this example is shown at the bottom of this page.
// -----------------------------------------------------------------------------------

// In this example, we'll load the Javascript function definition from a file.
// It doesn't need to come from a file.  It could just as easily be loaded from a string.
Dim sbScript As New Chilkat.StringBuilder
success = sbScript.LoadFile("js_call_function.js","utf-8")
If (success = False) Then
    System.DebugLog(sbScript.LastErrorText)
    Return
End If

// Note: Each instance of a Chilkat Js object automatically establishes
// its own internal runtime and context.  Applications do not need to explicitly create
// the JavaScript runtime or context.
Dim js As New Chilkat.Js

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

// Call Eval to add the function (shown at the bottom of this page) to the context's global object
success = js.Eval(sbScript,result)
If (success = False) Then
    // Examine the result for an exception.
    System.DebugLog(result.Emit())

    // Also examine the LastErrorText.
    System.DebugLog(js.LastErrorText)
    Return
End If

System.DebugLog(result.Emit())

// The expected output is "undefined":

// {
//   "type": "undefined",
//   "value": "undefined"
// }

//    When Eval processes a script containing only a function declaration,
//    it successfully performs the action (the function becomes defined).
//    However, since the script consists of a statement that produces no value,
//    the script's overall completion value is empty. In JavaScript, the
//    absence of a value is represented by `undefined`.
// 
//    Therefore, the Eval call returns `undefined`.

// ------------------------------------------------------------------------------
// Call the function calculateScore("Player1", 10, 20)

Dim funcCall As New Chilkat.JsonObject

// Create JSON defining the function call:

// {
//   "name": "calculateScore",
//   "args": [ "Player1", 10, 20 ]
// }

success = funcCall.UpdateString("name","calculateScore")
success = funcCall.UpdateString("args[0]","Player1")
success = funcCall.UpdateInt("args[1]",10)
success = funcCall.UpdateInt("args[2]",20)

funcCall.EmitCompact = False
System.DebugLog(funcCall.Emit())

success = js.CallFunction(funcCall,result)
If (success = False) Then
    // Examine the result for an exception.
    System.DebugLog(result.Emit())

    // Also examine the LastErrorText.
    System.DebugLog(js.LastErrorText)
    Return
End If

System.DebugLog(result.Emit())

// Output:

// {
//   "type": "int",
//   "value": 37
// }

Dim retval As Int32
retval = result.IntOf("value")
System.DebugLog("retval = " + Str(retval))