Now let's introduce another element to the application --- the Dots module --- which is used to indicate the total number of slides, and give context by highlighting the dot that represents the currently active slide.


If you haven't yet, create the file Dots.js, and add the code below to it. Read through all of the inline comments to understand how the dots area is constructed.

var DOMElement = require('famous/dom-renderables/DOMElement');

function Dots(node, options) {
    this.node = node;
   // Storage for all the children -- the 'dot' nodes
    this.dots = [];

    // Size and positioning for the individual dots
    this.dotWidth = options.dotWidth || 10;
    this.spacing = options.spacing || 5;

    // Determine how many children to add, and add them
    this.numPages = options.numPages;
    for (var i = 0; i < this.numPages; i++) {
        // Create new child node for each dot
        var dotNode = node.addChild();

        // Size the child
        dotNode.setAbsoluteSize(this.dotWidth, this.dotWidth)

        // Store child nodes in the dots array
        this.dots.push(new Dot(dotNode, i));

    // Highlight the first dot in the collection

// Evenly space out the dots
Dots.prototype.layoutDots = function(size) {
    if (size) {
        this.size = size;
    var totalDotSize = this.dotWidth * this.numPages + this.spacing * (this.numPages - 1);
    var start = (this.size[0] - totalDotSize) / 2;
    for (var i = 0; i < this.numPages; i++) {
        this.dots[i].node.setPosition(start + (this.dotWidth + this.spacing) * i, 0, 0);

// Updating the selected dots on change of current page.
Dots.prototype.pageChange = function(oldIndex, newIndex) {

module.exports = Dots;

Dot class

We'll also introduce a class Dot that will encapsulate an individual dot among the dots collection. You can think of a Dot as a grandchild of Carousel, carrying the visible element for each dot.

 * Dots.js
 * [complete file not shown]

function Dot(node, options) {
    this.node = node;
    this.el = new DOMElement(node);
    this.el.setProperty('borderRadius', '5px');
    this.el.setProperty('border', '2px solid white');
    this.el.setProperty('boxSizing', 'border-box');
} = function() {
    this.el.setProperty('backgroundColor', 'white');

Dot.prototype.deselect = function() {
    this.el.setProperty('backgroundColor', 'transparent');

Modified files: Dots.js | Carousel.js

Positioning the Dots

We will need to pass the scene size to the .layoutDots() method to get the dots evenly distributed across the screen. Instead of pinging the DOM for the width, we'll grab the size by registering an onSizeChange method within a resize component.

Add the code below to the Dots constructor.

// Add a component to keep dot layout updated
var resizeComponent = {
    onSizeChange: function(x, y, z) {
        // This will layout the dots whenever a resize occurs
        this.layoutDots([x, y, z])
        // Size === [parent size, 20, parent size]

Modified files: Dots.js

Now, whenever the node is resized, the method above will fire with the new size passed in. You can register an onSizeChange method with any component to get the current x,y,z size of a node. If a node doesn't have a size in a particular direction it will return the size of its parent.

Section recap: Code for this step

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