Source: button.js

/**
 * A Button component - 90% UX/COE Compliant<BR>
 * <BR><BR><img src=../images/button.png width=70% style="border:1px lime dashed";> 
 * <BR><BR><a href="../html/button.html">DEMO</a>
 */
class Button extends HTMLElement {
    constructor() {
        console.group("Button.constructor")
	
        super();
        console.groupEnd();
    };
    
    /**
     * Set observable values here. When Changed, attributeChangedCallback is invoked
     * @observedAttributes
     */
    static get observedAttributes() {
        console.group("Button.observedAttributes");
	this.observables = [];
	console.log(this.observables);
        console.groupEnd();
        return this.observables;
    };
    /**
     * This function is called when this is attached to DOM
     * @connectedCallback. 
     */
    connectedCallback() {
        console.group("Button.connectedCallback")
	
	let self = this;
	// MAKE SURE OUR COMPONENT HAS GLOBAL CLASS
	this.classList.add("wc");
	// FETCH ALL INTERESTING ELEMENTS
	this._fetchElements();
	// FETCH ALL ATTRIBUTES
	this._fetchAttributes();
	this.innerHTML = "<button type='button' class='" + this.properties.class + "'>" + this.dom.content + "</button>";
	if (!this.querySelector("button").classList.contains("btn-disabled")) {
	    this.addEventListener("click", function() {
		self._onClick();
	    });
	}
	// WRAP UP AND ADD STATS
	this._finalize();
	// SHOW IT NOW (NO FLICKERS) 
	this.style.visibility = "visible";
        console.groupEnd();
    };
    /**
     * Invoked When component is removed. Usually with a .remove() function call
     * @disconnectedCallback
     */
    disconnectedCallback() {
        console.group("Button.disconnectedCallback")
	/* CLEAN UP NOW */
        console.groupEnd();
    };
    /**
     * Called with .setAttribute(...) function call
     * @attributeChangedCallback
     */
    attributeChangedCallback(attr, oldval, newval) {
        console.group("Button.attributeChangedCallback:", attr, oldval, newval);
	this.properties = this.properties || [];
	switch(attr)
	{
	    case "class":
	    this.properties.class = newval;
	    break;
	}
	
        console.groupEnd();
    };
    /**
     * Stores DOM elements of interest for future use
     * @_fetchElements
     */
    _fetchElements() {
	console.group("Button._fetchElements");
	
	this.dom = this.dom || [];
	this.dom.content = this.innerHTML;
	console.groupEnd();
    };
    /**
     * Component attributes are _fetched and defaults are set if undefined
     * @_fetchAttributes
     * @param {string} [class=btn btn-primary btn-lg] button class
     */
    _fetchAttributes() {
	console.group("Button._fetchAttributes");
	
	this.properties = {
	    "cname"      : "Button",
	    "author"     : "Mel Heravi",
	    "version"    : "1.0"
	};
	if (this.hasAttribute("class")) {
	    this.properties.class = this.getAttribute("class");
	    $(this).removeClass(this.getAttribute("class"));
	    console.log("class: ", this.properties.class);
	}
	console.groupEnd();
    };
    /**
     * A sample callback usage function - see connectedCallback()
     * @_onClick
     */
    _onClick() {
	console.group("Button._onClick:", this.id);
	wc.publish(this, "wc-button", {
	    id: this.id,
	    action: "click"
	});
	console.groupEnd();
    };
    /**
     * Destroy the instance object and artifacts
     * @_destroy
     */
    destroy() {
	console.group("Message.destroy:", this.id);
	// FREE POINTER
	delete this;
	// REMOVE ITEM FROM DOM
	this.parentNode.removeChild(this);
	console.groupEnd();
    };
    /**
     * SAVE DATA FOR ANALYTICS
     * @__finalize
     */
    _finalize() {
	console.group("Button._finalize:", this.id);
	this.classList.add("wc");
	// ADD ANALYTICS HERE
	wc.getStats(this, this.properties.cname, this.properties.version);
	
	console.groupEnd();
    };
    /**
     * FOR TESTING PURPOSES
     * @test
     */
    static test() {
	console.group("Button.test");
	console.log("testing results will be printed here...");
	console.groupEnd();
	return true;
    }
}
window.customElements.define('wc-button', Button);