Modern JavaScript is considered a “safe” programming language. JavaScript does not give low-level access to CPU or memory, because it was created initially for browsers that do not usually require it. The capabilities of JavaScript greatly depend on the current environment it is operating in. For example, Node.js supports functions that permit JavaScript to perform network requests, write/read arbitrary files, etc. In-browser JavaScript could do anything related to interaction with the user, webpage manipulation, and the webserver. In addition, in-browser JavaScript is able to: 1.Add a new HTML to a page, update the existing content, improve styles. 2.Respond to user actions, pointer movements, run on mouse clicks and key presses. 3.Send numerous requests over the network towards remote servers, upload and download files. 4.Set and get cookies, show messages, ask questions to the visitor 5.Remembering the data of the client-side ( known as “local storage”). There are also some interesting things found in the Javascript world. Number as object type In other programming languages, usually, there is a difference of type for float and integer, but Javascript knows only one object type for numbers so there is no such thing in JavaScript as an integer that can be found from Mozilla docs. Undefined There is an “undefined’ value found on Javascript which is known as a value of type undefined that specifies an uninitialized value. Normally in other languages, the value (uninitialized) is similar to “null” or “nil”. However, Javascript has both null and undefined. Callback functions Functions are known as first-class objects in Javascript, user can easily pass a function as an argument towards another function and later on execute that passed-in function, or also return it to be even executed for later. This is the core of using the function of callback in JavaScript. These special functions are likely the widely and most used technique in JavaScript in functional programming and could create heaven or hell in your code if you are to use it wrongly. That is why it is often heard as a callback hell occurrence in the Javascript world. Competing in server side and front end Only Javascript can defeat the reign of intense popularity of programming language for both server side and front end developers. This is because Javascript contains NodeJs which is considered to be "JavaScript environment based on V8 Event-driven I/O server-side”. This could probably be the most captivating and one of a kind aspect of Javascript.