Example of Vanila Js and IIFEs

.js

(function(window)
{
    FTXCommon.ProductAttribute = {
        selectors: {
            accountSelect:      document.querySelector('[name="account_id"]'),
            attributeSetSelect: document.querySelector('.attributeSetSelect')
        },

        /**
         * Initialize
         *
         */
        init: function()
        {
            this.addHandlers();
        },

        /**
         * Add Handlers
         *
         */
        addHandlers: function()
        {
            var context = this;

            if(this.selectors.accountSelect)
            {
                this.selectors.accountSelect.onchange = function(event)
                {
                    context.getAttributeSet();
                };
            }
        },

        /**
         * Get Attribute Set
         *
         */
        getAttributeSet: function()
        {
            var accountId   = this.selectors.accountSelect.value;

            FTXCommon.Utils.emptySelect2(this.selectors.attributeSetSelect);

            // Add select box for finding department groups
            FTXCommon.Utils.addAjaxSelect2(this.selectors.attributeSetSelect, moduleConfig.attributeSetFindUrl, { placeholder: "Select Attribute Set"}, function(params)
            {
                return {
                    q:          params.term,
                    account_id: accountId,
                    page:       params.page
                };
            });
        },

        /**
         * Set AttributeSet Value
         *
         */
        setAttributeSetValue: function(value)
        {
            this.selectors.attributeSetSelect.value = value;

            var accountId   = this.selectors.accountSelect.value;

            // Add select box for finding department groups
            FTXCommon.Utils.addAjaxSelect2(this.selectors.attributeSetSelect, moduleConfig.attributeSetFindUrl, {}, function(params)
            {
                return {
                    q:          params.term,
                    account_id: accountId,
                    page:       params.page
                };
            });
        }
    }
})(window);