Visual Basic 6.0

Call a JavaScript Function Returning a String

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Demonstrates how to call a JavaScript function that returns a string. Visual Basic 6.0

Dim success As Long
success = 0

' This is the JavaScript function we'll call:

' function greet(name) {
'     return "Hello, " + name + "!";
' }

Dim sbScript As New ChilkatStringBuilder
success = sbScript.Append("function greet(name) { return ""Hello, "" + name + ""!""; }")

Dim js As New ChilkatJs

Dim result As New ChilkatJsonObject
result.EmitCompact = 0

' Call Eval to add the function to the context's global object
success = js.Eval(sbScript,result)
If (success = 0) Then
    ' Examine the result for an exception.
    Debug.Print result.Emit()

    ' Also examine the LastErrorText.
    Debug.Print js.LastErrorText
    Exit Sub
End If

' ------------------------------------------------------------------------------
' Call the function greet("Michael")

Dim funcCall As New ChilkatJsonObject

' Create JSON specifying the function name and arguments

' {
'   "name": "greet",
'   "args": [ "Michael" ]
' }

success = funcCall.UpdateString("name","greet")
success = funcCall.UpdateString("args[0]","Michael")

success = js.CallFunction(funcCall,result)
If (success = 0) Then
    ' Examine the result for an exception.
    Debug.Print result.Emit()

    ' Also examine the LastErrorText.
    Debug.Print js.LastErrorText
    Exit Sub
End If

Debug.Print result.Emit()

' Output:
' {
'   "type": "string",
'   "value": "Hello, Michael!"
' }

Dim retval As String
retval = result.StringOf("value")
Debug.Print retval

' Output:
' Hello, Michael!