Lianja

Call a JavaScript Function Returning an Integer

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

llSuccess = .F.

// ----------------------------------------------------------------------------------
// 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.
loSbScript = createobject("CkStringBuilder")
llSuccess = loSbScript.LoadFile("js_call_function.js","utf-8")
if (llSuccess = .F.) then
    ? loSbScript.LastErrorText
    release loSbScript
    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.
loJs = createobject("CkJs")

loResult = createobject("CkJsonObject")
loResult.EmitCompact = .F.

// Call Eval to add the function (shown at the bottom of this page) to the context's global object
llSuccess = loJs.Eval(loSbScript,loResult)
if (llSuccess = .F.) then
    // Examine the result for an exception.
    ? loResult.Emit()

    // Also examine the LastErrorText.
    ? loJs.LastErrorText
    release loSbScript
    release loJs
    release loResult
    return
endif

? loResult.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)

loFuncCall = createobject("CkJsonObject")

// Create JSON defining the function call:

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

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

loFuncCall.EmitCompact = .F.
? loFuncCall.Emit()

llSuccess = loJs.CallFunction(loFuncCall,loResult)
if (llSuccess = .F.) then
    // Examine the result for an exception.
    ? loResult.Emit()

    // Also examine the LastErrorText.
    ? loJs.LastErrorText
    release loSbScript
    release loJs
    release loResult
    release loFuncCall
    return
endif

? loResult.Emit()

// Output:

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

lnRetval = loResult.IntOf("value")
? "retval = " + str(lnRetval)


release loSbScript
release loJs
release loResult
release loFuncCall