Xbase++ Requires Chilkat v11.4.0+

Call a JavaScript Function Returning an Integer

See more JavaScript Examples

Demonstrates how to call a JavaScript function that returns an integer. Xbase++

LOCAL nSuccess
LOCAL oSbScript
LOCAL oJs
LOCAL oResult
LOCAL oFuncCall
LOCAL nRetval

nSuccess := 0

//  ----------------------------------------------------------------------------------
//  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.
oSbScript := CreateObject("Chilkat.StringBuilder")
nSuccess := oSbScript:LoadFile("js_call_function.js", "utf-8")
IF (nSuccess == 0)
    ? oSbScript:LastErrorText
    oSbScript:destroy()
    RETURN
ENDIF

//  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.
oJs := CreateObject("Chilkat.Js")

oResult := CreateObject("Chilkat.JsonObject")
oResult:EmitCompact := 0

//  Call Eval to add the function (shown at the bottom of this page) to the context's global object
nSuccess := oJs:Eval(oSbScript, oResult)
IF (nSuccess == 0)
    //  Examine the result for an exception.
    ? oResult:Emit()

    //  Also examine the LastErrorText.
    ? oJs:LastErrorText
    oSbScript:destroy()
    oJs:destroy()
    oResult:destroy()
    RETURN
ENDIF

? oResult: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)

oFuncCall := CreateObject("Chilkat.JsonObject")

//  Create JSON defining the function call:

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

oFuncCall:UpdateString("name", "calculateScore")
oFuncCall:UpdateString("args[0]", "Player1")
oFuncCall:UpdateInt("args[1]", 10)
oFuncCall:UpdateInt("args[2]", 20)

oFuncCall:EmitCompact := 0
? oFuncCall:Emit()

nSuccess := oJs:CallFunction(oFuncCall, oResult)
IF (nSuccess == 0)
    //  Examine the result for an exception.
    ? oResult:Emit()

    //  Also examine the LastErrorText.
    ? oJs:LastErrorText
    oSbScript:destroy()
    oJs:destroy()
    oResult:destroy()
    oFuncCall:destroy()
    RETURN
ENDIF

? oResult:Emit()

//  Output:

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

nRetval := oResult:IntOf("value")
? "retval = " + Str(nRetval)

oSbScript:destroy()
oJs:destroy()
oResult:destroy()
oFuncCall:destroy()

JavaScript

function calculateScore(name, pointsA, pointsB) {
    // Return length of name + both scores
    return name.length + pointsA + pointsB;
    }