Question

I’m working on a webpage for a class and am trying to work the navigation using ActionScript 3. My understanding of how it should work is that when you click the links at the top, it removes whatever is currently displayed, using removeChild, and adds the new page’s content using addChild.

It works fine when going from the initial page to one of the links. But whenever I go from a page that is not the home page to another page I get:

ArgumentError: Error #2025: The supplied DisplayObject must be a child
of the caller. at flash.display::DisplayObjectContainer/removeChild()
at nutshellMathReCoded4_fla::MainTimeline/hideOtherPages() at
nutshellMathReCoded4_fla::MainTimeline/runSubtraction()

Here is the code:

stop();
// Flash Imports
import flash.events.MouseEvent;
import flash.events.Event;
import flash.media.SoundMixer;

//Page Components //
// Home //
// Links
// Create Header & Nav //
// Logo Link
    var headerLogo:logoMainPage = new logoMainPage();
    headerLogo.x = 252.85;
    headerLogo.y = 18.00;
    //Addition Link
    var additionLink:addPageLink = new addPageLink();
    additionLink.x = 142.35;
    additionLink.y = 96.00;
    //Subtraction Link
    var subtractionLink:subPageLink = new subPageLink();
    subtractionLink.x = 208.60;
    subtractionLink.y = 144.60;
    // Multiplication Link
    var multiplicationLink:mulPageLink = new mulPageLink();
    multiplicationLink.x = 397.80;
    multiplicationLink.y = 100.00;
    // Division Link
    var divisionLink:divPageLink = new divPageLink();
    divisionLink.x = 597.95;
    divisionLink.y = 144.60;

//Animation
    var animation:mainAnimation = new mainAnimation();
    animation.x = 99.90;
    animation.y = 244.00;

//Addition // 
    var addSimpleX:additionSimpleX = new additionSimpleX();
    addSimpleX.x = 41;
    addSimpleX.y = 395.95;

    var addSimpleY:additionSimpleY = new additionSimpleY();
    addSimpleY.x = 364;
    addSimpleY.y = 395.95;

    var addSimpleAnswer:additionSimpleAnswer = new additionSimpleAnswer();
    addSimpleAnswer.x = 701;
    addSimpleAnswer.y = 395.95;

    var additionAddSign:additionSign = new additionSign();
    additionAddSign.x = 276.55;
    additionAddSign.y = 360.20;

    var additionEqualsSign:equalsSign = new equalsSign();
    additionEqualsSign.x = 613.95;
    additionEqualsSign.y = 360.20;

    var addSum:additionSummary = new additionSummary();
    addSum.x = 178.25;
    addSum.y = 202;

    var addTryOut:tryItOut = new tryItOut();
    addTryOut.x = 205.70;
    addTryOut.y = 475.65;

    var addDDLink:digDeeperLink = new digDeeperLink();
    addDDLink.x = 274.95;
    addDDLink.y = 696;

    var addTQLink:quizLink = new quizLink();
    addTQLink.x = 465;
    addTQLink.y = 696.50;

//Addition Deeper
    var addLong:additionExtended = new additionExtended();
    addLong.x = 193.00;
    addLong.y = 323.00;

    var addDDSum:additionDDSummary = new additionDDSummary();
    addDDSum.x = 222.40;
    addDDSum.y = 201.20;

    var addDDB2B:backToBasicsLink = new backToBasicsLink();
    addDDB2B.x = 271.95;
    addDDB2B.y = 696;

    var addDDTQ:quizLink = new quizLink();
    addDDTQ.x = 468;
    addDDTQ.y = 696;

//Subtraction
    var subSimpleX:subtractionSimpleX = new subtractionSimpleX();
    subSimpleX.x = 44;
    subSimpleX.y = 408.50;

    var subSimpleY:subtractionSimpleY = new subtractionSimpleY();
    subSimpleY.x = 367;
    subSimpleY.y = 408.50;

    var subSimpleAnswer:subtractionSimpleAnswer = new subtractionSimpleAnswer();
    subSimpleAnswer.x = 692.95;
    subSimpleAnswer.y = 408.50;

    var subtractionEqualsSign:equalsSign = new equalsSign();
    subtractionEqualsSign.x = 612.80;
    subtractionEqualsSign.y = 372.95

    var subtractionSubSign:subtractionSign = new subtractionSign();
    subtractionSubSign.x = 280.85;
    subtractionSubSign.y = 371.95;

    var subTryOut:tryItOut = new tryItOut();
    subTryOut.x = 221.8;
    subTryOut.y = 477.95;

    var subDDLink:digDeeperLink = new digDeeperLink();
    subDDLink.x = 274.95;
    subDDLink.y = 696;

    var subTQLink:quizLink = new quizLink();
    subTQLink.x = 465;
    subTQLink.y = 696.50;

    var subSum:subtractionSummary = new subtractionSummary();
    subSum.x = 147.30;
    subSum.y = 210.05;

// Subtraction Dig Deeper

    var subBudget:budget = new budget();
    subBudget.x = 367.95;
    subBudget.y = 400.90;

    var subExpenses:expenses = new expenses();
    subExpenses.x = 204.00;
    subExpenses.y = 513.40;

    var subDDT1:subtractionDD1 = new subtractionDD1();
    subDDT1.x = 264.05;
    subDDT1.y = 211;

    var subDDT2:subtractionDD2 = new subtractionDD2();
    subDDT2.x = 206.65;
    subDDT2.y = 351;

    var subDDT3:subtractionDD3 = new subtractionDD3();
    subDDT3.x = 131.80;
    subDDT3.y = 474.95;

    var subDDT4:subtractionDD4 = new subtractionDD4();
    subDDT4.x = 291.00;
    subDDT4.y = 463;

    var subCheckBudgetLink:checkBudgetLink = new checkBudgetLink();
    subCheckBudgetLink.x = 437;
    subCheckBudgetLink.y = 609.5;

    var subB2BLink:backToBasicsLink = new backToBasicsLink();
    subB2BLink.x = 271.95;
    subB2BLink.y = 696;

    var subDDTQLink:quizLink = new quizLink();
    subDDTQLink.x = 468;
    subDDTQLink.y = 696;

//Multiplication
    var mulSimpleX:multiplicationSimpleX = new multiplicationSimpleX();
    mulSimpleX.x = 30.85;
    mulSimpleX.y = 395.35;

    var mulSimpleY:multiplicationSimpleY = new multiplicationSimpleY();
    mulSimpleY.x = 370.85;
    mulSimpleY.y = 395.35;

    var mulSimpleAnswer:multiplicationSimpleAnswer = new multiplicationSimpleAnswer();
    mulSimpleAnswer.x = 691.90;
    mulSimpleAnswer.y = 395.35;

    var multiplicationMulSign:multiplicationSign = new multiplicationSign();
    multiplicationMulSign.x = 284.60;
    multiplicationMulSign.y = 365.95;

    var mulEqualsSign:equalsSign = new equalsSign();
    mulEqualsSign.x = 609.80;
    mulEqualsSign.y = 356.95;

    var mulSummary:multiplicationSummary = new multiplicationSummary();
    mulSummary.x = 145.30;
    mulSummary.y = 202.40;

    var mulTryOut:tryItOut = new tryItOut();
    mulTryOut.x = 218.80;
    mulTryOut.y = 461.95;

    var mulDDLink:digDeeperLink = new digDeeperLink();
    mulDDLink.x = 274.95;
    mulDDLink.y = 696;

    var mulTQLink:quizLink = new quizLink();
    mulTQLink.x = 465.00;
    mulTQLink.y = 696;



// Multiplication Deeper

    var mulDD1:multiplicationDD1 = new multiplicationDD1();
    mulDD1.x = 241.15;
    mulDD1.y = 209;

    var mulDD2:multiplicationDD2 = new multiplicationDD2();
    mulDD2.x = 297.05;
    mulDD2.y = 350.40;

    var mulDD3:multiplicationDD3 = new multiplicationDD3();
    mulDD3.x = 316.75;
    mulDD3.y = 393.65;

    var mulDD4:multiplicationDD4 = new multiplicationDD4();
    mulDD4.x = 297.55;
    mulDD4.y = 436.90;

    var mulB2BLink:backToBasicsLink = new backToBasicsLink();
    mulB2BLink.x = 271.95;
    mulB2BLink.y = 696;

    var mulDDTQL:quizLink = new quizLink();
    mulDDTQL.x = 468;
    mulDDTQL.y = 696;

// Division
    var divSimpleX:divisionSimpleX = new divisionSimpleX();
    divSimpleX.x = 42;
    divSimpleX.y = 397.5;

    var divSimpleY:divisionSimpleY = new divisionSimpleY();
    divSimpleY.x = 366.95;
    divSimpleY.y = 397.50;

    var divSimpleAnswer:divisionSimpleAnswer = new divisionSimpleAnswer();
    divSimpleAnswer.x = 698.95;
    divSimpleAnswer.y = 397.50;

    var divisionDivSign:divisionSign = new divisionSign();
    divisionDivSign.x = 277.80;
    divisionDivSign.y = 360.95;

    var divEqualsSign:equalsSign = new equalsSign();
    divEqualsSign.x = 609.80;
    divEqualsSign.y = 361.95;

    var divSummary:divisionSummary = new divisionSummary();
    divSummary.x = 112.50;
    divSummary.y = 202.20;

    var divTryOut:tryItOut = new tryItOut();
    divTryOut.x = 218.80;
    divTryOut.y = 466.95;

    var divDDLink:digDeeperLink = new digDeeperLink();
    divDDLink.x = 274.95;
    divDDLink.y = 696;

    var divTQLink:quizLink = new quizLink();
    divTQLink.x = 274.95;
    divTQLink.y = 696;

// Division Deeper

    var divDD1:divisionDD1 = new divisionDD1();
    divDD1.x = 239.60;
    divDD1.y = 215.00;

    var divDD2:divisionDD2 = new divisionDD2();
    divDD2.x = 328.65;
    divDD2.y = 336.70;

    var divDD3:divisionDD3 = new divisionDD3();
    divDD3.x = 308.95;
    divDD3.y = 381.20;

    var divB2BLink:backToBasicsLink = new backToBasicsLink();
    divB2BLink.x = 271.95;
    divB2BLink.y = 696;

    var divDDTQLink:quizLink = new quizLink();
    divDDTQLink.x = 468;
    divDDTQLink.y = 696;


// Quiz
    //Title
    var titleQuiz:quizTitle = new quizTitle();
    titleQuiz.x = 419.40;
    titleQuiz.y = 192;
    // Random Number Backgrounds
    var quizBG1:shortTextBG = new shortTextBG();
    quizBG1.x = 44.9;
    quizBG1.y = 283;

    var quizBG2:shortTextBG = new shortTextBG();
    quizBG2.x = 368.95;
    quizBG2.y = 283;

    var quizBG3:shortTextBG = new shortTextBG();
    quizBG3.x = 44.9;
    quizBG3.y = 360.25;

    var quizBG4:shortTextBG = new shortTextBG();
    quizBG4.x = 368.95;
    quizBG4.y = 360.25;

    var quizBG5:shortTextBG = new shortTextBG();
    quizBG5.x = 44.90;
    quizBG5.y = 440.20;

    var quizBG6:shortTextBG = new shortTextBG();
    quizBG6.x = 368.95;
    quizBG6.y = 440.20;

    var quizBG7:shortTextBG = new shortTextBG();
    quizBG7.x = 44.90;
    quizBG7.y = 518.80;

    var quizBG8:shortTextBG = new shortTextBG();
    quizBG8.x = 368.95;
    quizBG8.y = 518.80

    // Signs
    var quizAddSign:additionSign = new additionSign();
    quizAddSign.x = 280.05;
    quizAddSign.y = 251.90;

    var quizSubSign:subtractionSign = new subtractionSign();
    quizSubSign.x = 281.40;
    quizSubSign.y = 323.80;

    var quizMulSign:multiplicationSign = new multiplicationSign();
    quizMulSign.x = 288.20;
    quizMulSign.y = 414.05;

    var quizDivSign:divisionSign = new divisionSign();
    quizDivSign.x = 280.05;
    quizDivSign.y = 489.20;

    var quizAddEqualsSign:equalsSign = new equalsSign();
    quizAddEqualsSign.x = 603.90;
    quizAddEqualsSign.y = 251.90;

    var quizSubEqualsSign:equalsSign = new equalsSign();
    quizSubEqualsSign.x = 603.90;
    quizSubEqualsSign.y = 330.55;

    var quizMulEqualsSign:equalsSign = new equalsSign();
    quizMulEqualsSign.x = 603.90;
    quizMulEqualsSign.y = 409.20;

    var quizDivEqualsSign:equalsSign = new equalsSign();
    quizDivEqualsSign.x = 603.90;
    quizDivEqualsSign.y = 489.20;

    // Check quiz
    var quizCheck:checkQuiz = new checkQuiz();
    quizCheck.x = 369.95;
    quizCheck.y = 626.60;

    var answerWrong:wrongAnswer = new wrongAnswer();
    var answerCorrect:correctAnswer = new correctAnswer();


// Home Page //;

// Create Header & Nav //
// Logo
addChild(headerLogo);
addChild(additionLink);
addChild(subtractionLink);
addChild(multiplicationLink);
addChild(divisionLink);
addChild(animation);



headerLogo.addEventListener(MouseEvent.CLICK, runIndexPage);
function runIndexPage(e:MouseEvent):void
{
    // Hide other Pages
    hideOtherPages();

    addChild(animation);
    animation.gotoAndPlay(1);
}

// Addition Page //
additionLink.addEventListener(MouseEvent.CLICK, runAddition);
function runAddition(e:MouseEvent):void
{
    hideOtherPages();
    createAdditionPage();


}

subtractionLink.addEventListener(MouseEvent.CLICK, runSubtraction);
function runSubtraction(e:MouseEvent):void
{
        hideOtherPages();
        createSubtractionPage();
}

multiplicationLink.addEventListener(MouseEvent.CLICK, runMultiplication);
function runMultiplication(e:MouseEvent):void
{
        hideOtherPages();
        createMultiplicationPage();
}

divisionLink.addEventListener(MouseEvent.CLICK, runDivision);
function runDivision(e:MouseEvent):void
{
    hideOtherPages();
    createDivisionPage();
}


//Global Functions
function createAdditionPage():void
{
    addChild(addSimpleX);
    addChild(addSimpleY);
    addChild(addSimpleAnswer);
    addChild(additionAddSign);
    addChild(additionEqualsSign);
    addChild(addSum);
    addChild(addTryOut);
    addChild(addDDLink);
    addChild(addTQLink);
}

function createSubtractionPage():void
{
        addChild(subSimpleX);
        addChild(subSimpleY);
        addChild(subSimpleAnswer);
        addChild(subtractionSubSign);
        addChild(subtractionEqualsSign);
        addChild(subSum);
        addChild(subTryOut);
        addChild(subDDLink);
        addChild(subTQLink);
}

function createMultiplicationPage():void
{
        addChild(mulSimpleX);
        addChild(mulSimpleY);
        addChild(mulSimpleAnswer);
        addChild(multiplicationMulSign);
        addChild(mulEqualsSign);
        addChild(mulSummary);
        addChild(mulTryOut);
        addChild(mulDDLink);
        addChild(mulTQLink);
}

function createDivisionPage():void
{
        addChild(divSimpleX);
        addChild(divSimpleY);
        addChild(divSimpleAnswer);
        addChild(divisionDivSign);
        addChild(divEqualsSign);
        addChild(divSummary);
        addChild(divTryOut);
        addChild(divDDLink);
        addChild(divTQLink);
}

function hideOtherPages():void
{
    if(animation)
    {
        removeChild(animation);
        SoundMixer.stopAll();
    }

    else if(addSimpleX)
    {

        removeChild(addSimpleX);
        removeChild(addSimpleY);
        removeChild(addSimpleAnswer);
        removeChild(additionAddSign);
        removeChild(additionEqualsSign);
        removeChild(addSum);
        removeChild(addTryOut);
        removeChild(addDDLink);
        removeChild(addTQLink);
    }

    else if(addLong)
    {
        removeChild(addLong);
        removeChild(addDDSum);
        removeChild(addDDB2B);
        removeChild(addDDTQ);
    }

    else if(subSimpleX)
    {
        removeChild(subSimpleX);
        removeChild(subSimpleY);
        removeChild(subSimpleAnswer);
        removeChild(subtractionSubSign);
        removeChild(subtractionEqualsSign);
        removeChild(subSum);
        removeChild(subTryOut);
        removeChild(subDDLink);
        removeChild(subTQLink);
    }

    else if(subBudget)
    {
        removeChild(subBudget);
        removeChild(subExpenses);
        removeChild(subDDT1);
        removeChild(subDDT2);
        removeChild(subDDT3);
        removeChild(subDDT4);
        removeChild(subCheckBudgetLink);
        removeChild(subB2BLink);
        removeChild(subDDTQLink);
    }

    else if(mulSimpleX)
    {
        removeChild(mulSimpleX);
        removeChild(mulSimpleY);
        removeChild(mulSimpleAnswer);
        removeChild(multiplicationMulSign);
        removeChild(mulEqualsSign);
        removeChild(mulSummary);
        removeChild(mulDDLink);
        removeChild(mulTQLink);     
    }

    else if(mulDD1)
    {
        removeChild(mulDD1);
        removeChild(mulDD2);
        removeChild(mulDD3);
        removeChild(mulDD4);
        removeChild(mulB2BLink);
        removeChild(mulDDTQL);
    }

    else if(divSimpleX)
    {
        removeChild(divSimpleX);
        removeChild(divSimpleY);
        removeChild(divSimpleAnswer);
        removeChild(divisionDivSign);
        removeChild(divEqualsSign);
        removeChild(divSummary);
        removeChild(divTryOut);
        removeChild(divDDLink);
        removeChild(divTQLink);
    }

    else if(divDD1)
    {
        removeChild(divDD1);
        removeChild(divDD2);
        removeChild(divDD3);
        removeChild(divB2BLink);
        removeChild(divDDTQLink);
    }

    else if(titleQuiz)
    {
        removeChild(titleQuiz);
        removeChild(quizBG1);
        removeChild(quizBG2);
        removeChild(quizBG3);
        removeChild(quizBG4);
        removeChild(quizBG5);
        removeChild(quizBG6);
        removeChild(quizBG7);
        removeChild(quizBG8);
        removeChild(quizAddSign);
        removeChild(quizSubSign);
        removeChild(quizMulSign);
        removeChild(quizDivSign);
        removeChild(quizAddEqualsSign);
        removeChild(quizSubEqualsSign);
        removeChild(quizMulEqualsSign);
        removeChild(quizDivEqualsSign);
        removeChild(quizCheck);

        //Dynamic Quiz Removal Section ****
    }


}

Answer 1

This code looks terrifying, but I won’t dive into it as it is not the merits of the question. The problem is that you are only checking (in function hideOtherPages()) an existence of the objects, and not if they are added to Stage. You cannot remove from stage an object that is not there, this is why you gets this error, and it states just that.

1. You can check if your objects are added to stage before you will try to remove them.
2. You can remove all children from an object by simple loop.

The second option is the best in this case. You would create a Sprite, and…

var myContainer:Sprite = new Sprite();
addChild(myContainer);

// Here you are adding children/first set of visible objects
myContainer.addChild(myObject);
// ...

And now just before you will add new set of objects to container you can call “clearContainer()” function to remove previous ones.

function clearContainer() : void {
    while(myContainer.numChildren) {
        myContainer.removeChildAt(0);
    }
}

Your code will be GREATLY reduced because of this, as you won’t be forced to remove every item manually…

Alternatively if you want to keep a brute force, you can just check if objects exist before remove them manually, and you can do this by using function getChildByName(name:String) . You can set a property “name” for your objects and then check if “getChildByName” will return object or null, and if it is an object, you would remove it. So at the beginning it would look like this:

var divisionLink:divPageLink = new divPageLink();
divisionLink.x = 597.95;
divisionLink.y = 144.60;
divisionLink.name = "divisionLink"; // setting a name

And your removing would look like this:

else if(divisionLink && this.getChildByName("divisionLink"))
{
    removeChild(divisionLink);
}

And do this with every item. This is tedious and slow, so I wouldn’t recommend it, but included it for educational purposes.