Programs
JavaScript, as most programmers already know, is an open-source scripting language. It is made for developing web-based apps. It is significantly quicker than other languages since it is easy to learn and interpretable. It is quite known that both HTML and JavaScript are interlinked. Given this, using JavaScript in web-based applications has become simpler than ever.
The Hero Vired team has put together a comprehensive list of the best Javascript Interview Questions and Answers to help you ace the job interview and earn your dream position as a Javascript Programmer.
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Given its exceptional performance and next-level capabilities, most big corporations like Netflix and Google are now applying JavaScript in the majority of their operations. You must be competent and knowledgeable enough to clear your online assessment round and answer the JavaScript interview questions to secure a position as a web developer in one such corporation.
To help you prepare for all JavaScript questions, Hero Vired presents a guide to JavaScript interview questions and answers.
We bring to you the top JavaScript interviews questions with sample answers that would help demonstrate your knowledge of the industry and the job role.
Brendan Eich, a Netscape programmer, created JavaScript. JavaScript was originally known as Mocha when it first debuted. Following that, it was referred to as Live Script until it became JavaScript. Web browsers that support object-oriented scripting may understand and carry out JavaScript code when it is put into HTML pages.
JavaScript has a number of features, including:
JavaScript needs no introduction as it’s a highly recognized scripting language in the programming world. It is distinct from Java language.
It is a lightweight, object-based, cross-platform translation language frequently utilized for client-side validation. The JavaScript Translator must interpret the JavaScript code for the web browser, which is built into the browser.
The benefits of JavaScript are as follows:
Let’s move to the next javascript interview question.
One of the most important JavaScript interview questions is what hoisting is. The way that JavaScript operates by default is called hoisting, meaning that all variable and function declarations are shifted to the top. Hoisting, to put it simply, is the procedure of moving variables and functions up to the apex of the scope, regardless of where they’ve been declared. The reach can be local or international.
Often, interviewers start with basic JavaScript interview questions, such as the data types available in JavaScript. Simply tell, JavaScript consists of two data types:
When it comes to JavaScript interview questions and answers, prepare this comparative analysis answer to what distinguishes var and let keywords. In JavaScript, both let and var keywords are leveraged to declare variables. Nevertheless, they have their differences, such as
| Particulars | let | var |
|---|---|---|
| Redeclaration | Not Permitted | Permitted |
| Scope | Block Scope | Function Scope |
| Hoisting | Never Happens | Happens occasionally |
| Block-level speed | Available | Unavailable |
The NaN function in JavaScript is applied to check if a value is NaN (Not a number) or of the type “Number.” The expression NaN is a type of number in JavaScript. This is yet one of the JavaScript interview questions that you must stay aware of.
Let’s move to the next javascript interview question.
Such javascript interview questions can be difficult but here’s a hint.
Immediately Invoked Functions, often known as IIFEs or IIFYs, begin operating as soon as they are specified. Syntax:
(function()
{
// Do something;
})
();
A brand-new tool in ECMAScript 5 called JavaScript Strict Mode enables you to create a function or code in a “strict” operational setting. This language typically throws errors that are “not especially severe.” Yet, in “Strict mode,” all errors, even silent faults, will result in a throw. Debugging hence becomes easier. This reduces the likelihood of programming errors.
Self Invoking Functions are automatic function expressions that are invoked without a request when they are followed by (). However, the function declaration cannot be used by itself to call the function.
Knowing about the differences between exec() and test() will come in handy when preparing JvaScript interview questions and answers.
| Test () methods | Exec () methods |
|---|---|
| A string can be searched for a specified pattern using the JavaScript expression method exec(). | If the pattern is discovered, it will be directly returned; else, it will produce an “empty” result. |
| A string can be searched for a certain pattern or text using the JavaScript expression method test (). | A string can be searched for a certain pattern or text using the JavaScript expression method test (). |
| When it is discovered, the pattern will either return the Boolean value “true” or “false.” | When it is discovered, the pattern will either return the Boolean value “true” or “false.” |
The scope of a JS program controls which parts of the code allow access to variables and functions. In general, the scope will inform us of the variables and functions we can and cannot access at a particular location in the code. In JS, there are three different scope types:
External JavaScript is JavaScript code (script) that is created in a different file with the extension.js. This file is linked inside the head> or body> element of the HTML file, depending on where the code is to be inserted. Several benefits of external Javascript include
It makes it possible for web developers and designers to work together on HTML and javascript files. The code is reusable. External JavaScript has simple code that is easy to read.
Let’s move to the next JavaScript interview question.
Currying is also an important term asked in one of the JavaScript questions. Currying is the method of breaking down a function with many arguments into a series of functions, each containing just one argument. It is a mathematical technique that bears Haskell Curry’s name.
An n-ary function can become a unary function by performing currying. To illustrate how an n-ary function becomes a currying function, let’s look at an example.
You may anticipate being asked one of the most common JavaScript interview questions: ‘what are the types of JS errors?’ Well, in javascript, there are two distinct forms of errors.
Such javascript interview questions can be difficult but here’s a hint.
The interviewer may test your knowledge of JavaScript’s constructor function, too, by asking one of the related JavaScript interview questions. Single or many objects with similar characteristics and methods can be created using constructor functions. Example:
DOM or document object model represents the HTML document. It can be utilized to access and modify HTML information. Keeping your answer simple and concise for one such JavaScript question is good.
JavaScript’s variables serve as a representation of the arguments supplied to functions.
The object that represents a browser window is produced automatically by the browser. There is no JavaScript object for it. That thing is a browser object. The popup dialogue box is shown using the window object.
Let’s move to the next JavaScript interview question.
In JavaScript, comments can be of two different types.
| JavaScript | JScript |
|---|---|
| Oracle Corporation owns this scripting language | Microsoft owns this scripting language |
| No provision for active content creation | Capable of creating active content online |
| The codes can run and compile in any website browser | The codes can run and compile only in the Microsoft browser |
| It’s implementation isn’t limited to any particular browser | It’s limitation is limited only to the Microsoft browser |
| Based on ECMAScript | Based on ECMAScript from Microsoft |
Hopefully, with these Js interview questions and answers, you now have the knowledge and a better grasp of the JavaScript questions that interviewer may ask in your coming interview. Being aware and knowing all these JavaScript interview questions and their responses is all good.
However, what should one do to acquire the skills to benefit from JavaScript’s popularity? No worries as Hero Vired has a solution for everything. With Hero Vired’s full-stack development course, you’ll never have to find answers to any Js interview questions whatsoever.
Updated on April 24, 2024
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