Both are looping constructs. ‘for in’ iterates over all enumerable property keys of an object. ‘for of’ iterates over the values of an iterable object. What are reference types? Reference types include arrays, objects and functions.

Continuous integration/ continuous deployment pipeline is a series of steps which must be performed in order to deliver a new version of software. building testing and deploying.

Asynchronous javascript and xml. (name is misleading - JSON/plain text as common as XML) AJAX allows web pages to be updated asynchronously, by exchanging data with a web server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.