Some interview question in JavaScript

For interactive our website we uses some scripts, its JavaScript.

JavaScript is a lightweight, single-threaded, just-in-time compiled programming language. While it is the most well-known scripting language for Web pages, many non-browser environments also use it, such as Node.js

JavaScript is front-end or back-end or client-side or server-side

How works JavaScript

Truthy and Falsy

🔴Undefined, Null, and NaN (Not a Number) values are false. 🔴If variable set by false, it is falsy.

Undefined VS Null

Null means not exists

🟢Value is not set. 🟢If function is not return or return but not said what is returned. 🟢If parameter is not pass. 🟢If property is not set in object 🟢If value is set undefined

Double equal (==) vs Triple equal (===)


Bubble Event

Event bubble work this way

Recursive vs Iteration function


Callback function

Get vs Post

Post: For to submission data server send a request its post. Normally all request send in body. It has no limit.