Read this free guide below with common Javascript Developer interview questions
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Javascript is an essential programming language for developing interactive, user-friendly websites. A skilled Javascript developer can create dynamic web pages that respond to user inputs, and make your website stand out in a crowded online marketplace. If you're planning on interviewing a Javascript developer, here are 20 questions to help you gauge their expertise in the job.
Javascript is a scripting language used to build interactive and dynamic web pages. It allows developers to create rich user interfaces, animations, client-side validation, and handle events. It is widely used for web development, and it is the only language that runs natively in web browsers, meaning that it doesn't need to be compiled to be executed.
ES6, also known as ECMAScript 2015, is the latest version of Javascript that introduced several new features, including:
The let keyword declares a variable that can be reassigned, while const declares a variable that cannot be reassigned. Var declares a variable globally or locally to a function, while let and const declare variables only in the block scope.
Callbacks are functions that are passed as arguments to other functions and are executed later, usually after some asynchronous operation finishes.
Closures are functions that have access to variables in their lexical scope, even when they're called outside that scope.
Null is a value that represents no value or an empty state intentionally assigned by the developer, while undefined is a value assigned automatically by Javascript to indicate that a variable hasn't been assigned a value.
Synchronous programming executes code in a sequential order, blocking until a function finishes executing, while asynchronous programming allows code to run concurrently and doesn't block other code from running.
Hoisting is a feature in Javascript where variable and function declarations are moved to the top of their respective scopes, allowing them to be accessed before they're declared.
Event bubbling is a feature in Javascript where events travel up the DOM tree from the target element to the parent elements until it reaches the document object.
Event capturing is the opposite of event bubbling, where events are fired from the uppermost ancestor and travels down the DOM tree to the target element.
Event.preventDefault stops the default behaviour of an event, while event.stopPropagation prevents an event from propagating up the DOM tree.
There are several ways to create objects in Javascript, including:
A Promise is a way to handle asynchronous operations and perform actions based on their results. It represents a value that may not be available yet but will eventually be resolved.
Async/await is a syntax that allows functions to wait for a Promise to resolve before continuing its execution. It makes asynchronous code look and behave like synchronous code, making it easier to read and write.
Template literals allow developers to include variables or expressions in a string literal by wrapping them with ${}.
Native libraries are built into Javascript and provide core functionalities, while third-party libraries are created by external developers and offer optional functionalities to make development easier and faster.
Using libraries and frameworks make development faster and less prone to errors, standardized, and provides support for cross-browser compatibility.
Client-side scripting runs on the client-side (browser), while server-side scripting runs on the server-side (web server).
Some of the best practices for writing efficient and secure Javascript code include:
Debugging Javascript code can be done using the console, console.log(), breakpoints, and debugger statements.
These are some of the fundamental questions that you can ask a Javascript developer during the interview process. It is essential to assess the candidate's skills, experience, and knowledge of the language to ensure that they are the right fit for your organization.
As a Javascript developer, it is essential to be well-prepared for interviews to land your dream job. Here are some tips to help you prepare for a Javascript developer interview:
By following these tips, you can improve your chances of acing the Javascript Developer interview and landing your dream job. Remember to showcase your skills, experience and enthusiasm towards Javascript development and the position being applied for.
If you fail to research the company and the role you're applying for, you risk appearing unprepared and uninterested. Prior to the interview, learn about the company's mission, its products/services, and the role's responsibilities.
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