Xojo Plugin

Call a JavaScript Function Returning a Boolean

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

Dim success As Boolean
success = False

// This is the JavaScript function we'll call:

// function isEven(number) {
//     return number % 2 === 0;
// }

Dim sbScript As New Chilkat.StringBuilder
success = sbScript.Append("function isEven(number) { return number % 2 === 0; }")

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.
    System.DebugLog(result.Emit())

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

// ------------------------------------------------------------------------------
// Call the function isEven(8)

Dim funcCall As New Chilkat.JsonObject

// Create JSON specifying the function name and arguments

// {
//   "name": "isEven",
//   "args": [ 8 ]
// }

success = funcCall.UpdateString("name","isEven")
success = funcCall.UpdateInt("args[0]",8)

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": "bool",
//   "value": true
// }

Dim retval As Boolean
retval = result.BoolOf("value")
System.DebugLog(Str(retval))

// Output:
// True