Lianja

Call a JavaScript Function Returning an Integer

See more JavaScript Examples

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

JavaScript

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