B4X Requires Chilkat v11.4.0+

Call a JavaScript Function Returning a Boolean

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Demonstrates how to call a JavaScript function that returns a boolean. B4X

Dim success As Boolean = False

'  This is the JavaScript function we'll call:

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

Dim sbScript As ChilkatStringBuilder
sbScript.Initialize
sbScript.Append("function isEven(number) { return number % 2 === 0; }")

Dim js As ChilkatJs
js.Initialize("js")

Dim result As ChilkatJsonObject
result.Initialize
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.
    Log(result.Emit)

    '  Also examine the LastErrorText.
    Log(js.LastErrorText)
    Return
End If


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

Dim funcCall As ChilkatJsonObject
funcCall.Initialize

'  Create JSON specifying the function name and arguments

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

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

success = js.CallFunction(funcCall, result)
If success = False Then
    '  Examine the result for an exception.
    Log(result.Emit)

    '  Also examine the LastErrorText.
    Log(js.LastErrorText)
    Return
End If


Log(result.Emit)

'  Output:
'  {
'    "type": "bool",
'    "value": true
'  }

Dim retval As Boolean = result.BoolOf("value")
Log(retval)

'  Output:
'  True