Learning jQuery 3 - Fifth Edition

Enabling method chaining

In addition to implicit iteration, jQuery users should be able to rely on chaining behavior. This means that we need to return a jQuery object from all plugin methods, unless the method is clearly intended to retrieve a different piece of information. The returned jQuery object is usually just the one provided as this. If we use .each() to iterate over this, we can just return its result:

(function($) {  $.fn.swapClass = function(class1, class2) {    return this      .each((i, element) => {        const $element = $(element);        if ($element.hasClass(class1)) {          $element            .removeClass(class1)            .addClass(class2);        } else if ($element.hasClass(class2)) {          $element            .removeClass(class2)            .addClass(class1);        }      });  };})(jQuery); 

Listing 8.10