B4X Requires Chilkat v11.4.0+

Call a JavaScript Function Returning a String

See more JavaScript Examples

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

Dim success As Boolean = False

'  This is the JavaScript function we'll call:

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

Dim sbScript As ChilkatStringBuilder
sbScript.Initialize
sbScript.Append("function greet(name) { return " & Chr(34) & "Hello, " & Chr(34) & " + name + " & Chr(34) & "!" & Chr(34) & "; }")

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 greet("Michael")

Dim funcCall As ChilkatJsonObject
funcCall.Initialize

'  Create JSON specifying the function name and arguments

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

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

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": "string",
'    "value": "Hello, Michael!"
'  }

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

'  Output:
'  Hello, Michael!