JS Plugin Boilerplate

myPlugin.js

// Create an immediately invoked functional expression to wrap our code
(function() {

    // Define our constructor 
    this.myPlugin = function() {

        // Create global element references
        this.element = null;

        // Define option defaults 
        let defaults = {
            selector: 'body',
            element: null,
            className: 'my-plugin',
            htmlContent: '<h1>Hello World!</h1>',
        };

        // Create options by extending defaults with the passed in arugments
        if (arguments[0] && typeof arguments[0] === "object") {
            this.options = extendDefaults(defaults, arguments[0]);
        }

        pluginInit.call(this);

    };
    
    /**
     * Public Methods
     */
    myPlugin.prototype.test = function() {
        console.log('Test Ok!');
    };

    myPlugin.prototype.destroy = function() {
        pluginDestroy.call(this);
    };
    
    
    /**
     * Private Methods
     */
    function pluginInit() {

        let innerContent;

        // Get base element
        if (typeof this.options.element == "undefined" || this.options.element == null)
            this.element = document.querySelector(this.options.selector);
        else
            this.element = this.options.element;

        console.log(this.element);

        // Create element
        innerContent = document.createElement("div");
        innerContent.innerHTML = this.options.htmlContent;

        // Append innerContent to body
        this.element.appendChild(innerContent);

        // Add base plugin className
        this.element.className = this.options.className;

    }

    function pluginDestroy() {
        let innerContent;
        innerContent = document.getElementsByName("div");
        this.element.removeChild(innerContent);
        this.element.className.replace(this.options.className, "");
    }

    function extendDefaults(options, properties) {
        let property;
        for (property in properties) {
            if (properties.hasOwnProperty(property)) {
                options[property] = properties[property];
            }
        }
        return options;
    }

}());

var plugin = new myPlugin({
    element: element,
    className: 'my-plugin',
    htmlContent: '<h1>Hello World!</h1>',
});