Unobtrusive JavaScript is a general term that conveys a general philosophy, similar to the term REST (Representational State Transfer). The high-level description is that unobtrusive JavaScript doesn’t intermix JavaScript code in your page markup.

Each function is used to iterate each and every element of an object. It is used to loop DOM elements, arrays and the object properties.

Following are the basic selectors in jQuery: Element ID CSS Name Tag Name DOM hierarchy