Basic Javascript Interview Questions:
- What are the different data types present in javascript? …
- Explain Hoisting in javascript. …
- Difference between “ == “ and “ === “ operators. …
- Explain Implicit Type Coercion in javascript. …
- Is javascript a statically typed or a dynamically typed language?
Indeed, What are objects in JavaScript?
In JavaScript, an object is a standalone entity, with properties and type. Compare it with a cup, for example. A cup is an object, with properties. A cup has a color, a design, weight, a material it is made of, etc. The same way, JavaScript objects can have properties, which define their characteristics.
Then, What is array in JavaScript? Arrays are a special type of objects. The typeof operator in JavaScript returns “object” for arrays. But, JavaScript arrays are best described as arrays. Arrays use numbers to access its “elements”.
Why is JavaScript used? Javascript is used by programmers across the world to create dynamic and interactive web content like applications and browsers. JavaScript is so popular that it’s the most used programming language in the world, used as a client-side programming language by 97.0% of all websites.
In the same way What are promises in JavaScript? A Promise is a JavaScript object that links producing code and consuming code.
What is JavaScript closure?
A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function’s scope from an inner function.
What are properties in JavaScript?
A JavaScript property is a characteristic of an object, often describing attributes associated with a data structure. There are two kinds of properties: Instance properties hold data that are specific to a given object instance. Static properties hold data that are shared among all object instances.
What is DOM in JavaScript?
The Document Object Model (DOM) is the data representation of the objects that comprise the structure and content of a document on the web.
What are the datatypes in JavaScript?
JavaScript types
- Boolean type.
- Null type.
- Undefined type.
- Number type.
- BigInt type.
- String type.
- Symbol type.
What is string in JavaScript?
A string can be any text inside double or single quotes: let carName1 = “Volvo XC60”; let carName2 = ‘Volvo XC60’; String indexes are zero-based: The first character is in position 0, the second in 1, and so on.
What are the types of JavaScript?
JavaScript types
- Boolean type.
- Null type.
- Undefined type.
- Number type.
- BigInt type.
- String type.
- Symbol type.
Who uses JavaScript?
There are over 1.6 billion web sites in the world, and JavaScript is used on 95% of them (1.52 billion web sites with JavaScript). By virtue of this fact, virtually every computing device in use today runs JavaScript, including iPhones, Android phones, Apple Mac OS, Microsoft Windows, Linux, smart TVs, etc.
What is Arrow function in JavaScript?
Arrow function is one of the features introduced in the ES6 version of JavaScript. It allows you to create functions in a cleaner way compared to regular functions. For example, This function // function expression let x = function(x, y) { return x * y; }
What is async and await in JavaScript?
1. The word “async” before a function means one simple thing: a function always returns a promise. 2. The keyword “await” makes JavaScript wait until that promise settles and returns its result.
What are prototypes in JavaScript?
Prototypes are the mechanism by which JavaScript objects inherit features from one another. In this article, we explain what a prototype is, how prototype chains work, and how a prototype for an object can be set.
What is scope in JavaScript?
The scope is a policy that manages the availability of variables. A variable defined inside a scope is accessible only within that scope, but inaccessible outside. In JavaScript, scopes are created by code blocks, functions, modules.
What is the type of null in JavaScript?
In JavaScript null is “nothing”. It is supposed to be something that doesn’t exist. Unfortunately, in JavaScript, the data type of null is an object. You can consider it a bug in JavaScript that typeof null is an object.
How many types of objects are there in JavaScript?
There are two types of object properties: The data property and the accessor property. Note: Each property has corresponding attributes. Attributes are used internally by the JavaScript engine, so you cannot directly access them.
What are methods in JavaScript?
JavaScript methods are actions that can be performed on objects. A JavaScript method is a property containing a function definition.
What is document in JavaScript?
JavaScript Document object is an object that provides access to all HTML elements of a document. When an HTML document is loaded into a browser window, then it becomes a document object. The document object stores the elements of an HTML document, such as HTML, HEAD, BODY, and other HTML tags as objects.
What is jQuery and how do you use it?
jQuery is a lightweight, “write less, do more”, JavaScript library. The purpose of jQuery is to make it much easier to use JavaScript on your website. jQuery takes a lot of common tasks that require many lines of JavaScript code to accomplish, and wraps them into methods that you can call with a single line of code.
What is this bootstrap?
Bootstrap is a free and open source front end development framework for the creation of websites and web apps. The Bootstrap framework is built on HTML, CSS, and JavaScript (JS) to facilitate the development of responsive, mobile-first sites and apps.
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