Source: carousel2.js

/**
 * Carousel2 Component<BR>
 * <BR><BR><img src=/tk/lib/components/w/img/carousel2.png width=30% style="border:1px lime dashed;padding:20px">
 * <BR><BR><a href="/tk/lib/components/w/html/carousel2.html">DEMO</a>
 */
class Carousel2 extends HTMLElement {
    constructor() {
        wc.group("Carousel2.constructor")
	
        super();

        wc.groupEnd();
    };
    
    /**
     * Set observable values here. When Changed, attributeChangedCallback is invoked
     * @observedAttributes
     */
    static get observedAttributes() {
        wc.group("Carousel2.observedAttributes");

	this.observables = [];

        wc.groupEnd();
        return this.observables;
    };

    /**
     * Called when this is attached to DOM
     * @connectedCallback. 
     */
    connectedCallback() {
        wc.group("Carousel2.connectedCallback")
	
	// ADD A RANDOM ID IF NONE EXIST
	if (!this.id) {
	    this.id = this.constructor.name.toLowerCase() + "-" + wc.uid();
	}

	// GET PROPERTIES AND INTERESTING ELEMENTS
	this._initialize();

	// ADD COMPONENT MARKTOP
	this.innerHTML = `
	    <div id="${this.id}-actual" class="carousel slide" data-ride="carousel">
		<ol class="carousel-indicators">
		</ol>

		<div class="carousel-inner" role="listbox">
		</div>

		<a class="carousel-control-prev" href="#${this.id}-actual" role="button" data-slide="prev">
		    <span class="carousel-control-prev-icon" aria-hidden="true"></span>
		    <span class="sr-only">Previous</span>
		</a>

		<a class="carousel-control-next" href="#${this.id}-actual" role="button" data-slide="next">
		    <span class="carousel-control-next-icon" aria-hidden="true"></span>
		    <span class="sr-only">Next</span>
		</a>
	    </div>`;

	this.configure();

	// ADD STATS AND OTHER FINAL STUFF
	this._finalize();

        wc.groupEnd();
    };

    /**
     * Called with .setAttribute(...) function call
     * @attributeChangedCallback
     */
    attributeChangedCallback(attr, oldval, newval) {
        wc.group("Carousel2.attributeChangedCallback:", attr, oldval, newval);

	this.properties = this.properties || [];

	let obs = Carousel2.observedAttributes;

	for (let i = 0; i < obs.length; i++) {
	    if (newval) {
		this.properties[obs[i]] = newval;
	    }
	}
	
	// YOUR CODE FOR CHANGES GO HERE (MAYBE NULL FIRST TIME THROUGH)
	try {
	    switch(attr) 
	    {
		case "header":
		//this.querySelector("h1").innerHTML = newval;
		break;
		
		default:
		break;
	    }
	} catch(e) {
	    wc.warn(e.name + ' > ' + e.message);
	}

        wc.groupEnd();
    };

    /**
     * Component attributes are _fetched and defaults are set if undefined
     * @private
     * @_fetchAttributes
     */
    _fetchAttributes() {
	wc.group("Carousel2._fetchAttributes");
	
	this.properties = {
	    uparam	: "",
	    cname	: "Carousel2",
	    author	: "Mel M. Heravi",
	    version	: "1.0",
	    active	: 0
	};
	
	// SAVE WIDGET SPECIFIC PROPERTIES
	this.propertiesW = [];
	
	// SAVE ALL OTHER PROPERTIES
	let attrs = wc.getAttributes(this)
	
 	for (var key in attrs) {
	    let attr = this.getAttribute(key) || this.properties.key;
	    this.properties[key]  = this.getAttribute(key);
	    this.propertiesW[key] = this.getAttribute(key);
	    wc.log(key + ": " + attrs[key]);
	}

	// SET ALL INITIAL ATTRIBUTES
 	for (var key in this.properties) {
	    switch(key) 
	    {
		case "header":
		break;
		
		default:
		break;
	    }
	}

	wc.log("ATTRIBUTES: ", this.properties);

	wc.groupEnd();
    };

    /**
     * configure the instance object and artifacts
     * @configure
     * @param {string} data use data if exist else use 'this.properties.cfg' parameter
p     */
    configure(data) {
	wc.group("Carousel2.configure:", data);

	// IF JSON VARIABLE (data) IS PROVIDED
	if (data) {
	    this._process(data);
	} else {
	    let self = this;

	    $.getJSON(this.properties.cfg, function(data) {
		self._process(data);
	    }).fail(function(jqXHR, textStatus, errorThrown) {
		alert("ERROR: INCOMING TEXT " + jqXHR.responseText);
	    });
	}

	wc.groupEnd();
    };

    /**
     * _process the instance object and artifacts
     * @private
     * @_process
     */
    _process(data) {
	wc.group("Carousel2._process:", data);
	
	let ind = this.querySelector(".carousel-indicators");
	let inn = this.querySelector(".carousel-inner");

	for (var i = 0; i < data.length; i++) {
	    let cls = "";
	    if (this.properties.active == i) {
		cls = "active";
	    }

	    $(ind).append(`<li data-target="#${this.id}-actual" data-slide-to="${i}" class="${cls}"></li>`);

	    $(inn).append(`
		<div class="carousel-item ${cls}">
		    <img src="${data[i].img}" data-holder-rendered="true">

		    <div class="carousel-caption d-none d-md-block">
			<h3>${data[i].header}</h3>
			<p>${data[i].description}</p>
		    </div>
		</div>
	    `);
	}
	
	wc.groupEnd();
    };

    /**
     * Initialize component
     * @private
     * @_initialize
     */
    _initialize() {
	wc.group("Carousel2._initialize:", this.id);

	// FETCH ALL ATTRIBUTES
	this._fetchAttributes();
	
	wc.groupEnd();
    };

    /**
     * Save data for analytics and final wrap up
     * @private
     * @_finalize
     */
    _finalize() {
	wc.group("Carousel2._finalize:", this.id);

	this.classList.add("wc");

	// ADD ANALYTICS HERE
	wc.setStats(this, this.properties.cname, this.properties.version);
	
	// SHOW IT NOW (NO FLICKERS) 
	this.style.visibility = "visible";

	wc.groupEnd();
    };

    /**
     * Invoked When component is removed. Usually with a .remove() function call
     * @disconnectedCallback
     */
    disconnectedCallback() {
        wc.group("Carousel2.disconnectedCallback")

	// FREE MEMORY AND CLEANUP

        wc.groupEnd();
    };

    /**
     * Destroy the instance object and artifacts
     * @destroy
     */
    destroy() {
	wc.group("Carousel2.destroy");

	// FREE ALL MEMORY
	// you should delete all created objects here
	
	// FREE POINTER
	delete this;
	
	// REMOVE ITEM FROM DOM
	this.parentNode.removeChild(this);

	wc.groupEnd();
    };
}

window.customElements.define('wc-carousel2', Carousel2);