Deleting nodes in Scene.

Question

Hi,
I have a fully working 'JavaFX create graphics application' (e.g. y = x^2). But unfortunately, I did not succeed to delete the previous line after creating a new graphic line. I already tried to delete the regarding nodes by using an id. That seemed to work (it prints the message 'deleted' on the next line), but unfortunately I still see the previous line on the screen. Any body have some idea how to delete the previous line?
I hope someone can help me. Thanks!
import ...
var sceneRef : Scene;
var textBox : TextBox;
Stage {
    title: "Draw Graphics"
    scene: sceneRef = Scene {
        width: 980
        height: 700
        content: [
            textBox = TextBox {
                layoutX:30
                layoutY:30
                text: "x"
            Button {
                layoutX : 230
                layoutY: 30
                text: "Draw!"
                action: function() {
                     draw();
         // etc...
function draw() : Void {
    // delete previous line
    for(i in [0..sizeof sceneRef.content]){
        if(sceneRef.content.id == "textRefId"){
delete sceneRef.content[i] from sceneRef.content; //this does not work!
println("deleted"); //prints 'deleted'
// draw new line
for (xxx in [0.0 .. 32.0 step 0.01]) {
var textRef = Text {
id: "textRefId"
layoutX: getRealX(xxx)
layoutY: getRealY(calculateY(xxx))
content: "."
fill: Color.BLUE
insert textRef into sceneRef.content;
// etc other functions...

Answer 1

First, there is a thing that strikes me: you create lot of objects with same ID. See Node's ref., at String ID: "+Each node in the scene graph can be given a unique id. This id is much like the "id" attribute of an HTML tag in that it is up to the designer and developer to ensure that the id is unique within the scene graph.+"
You can use styleClass if you want a way to mark the nodes.
But it might be more efficient to add a Group to the scene and to put your "points" there. Thus you can just delete and re-create the group to get rid of everything at once.
I wonder why you use Text nodes for the points, why not Circle? Or, even, Line between previous point and current one?