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#efefef}.footer{padding-top:3rem}.footer-text{font-size:.8rem}</style></head><body class=""><div class="topbar"></div><div class="container"><a class="skip-link" href="#main-content">Skip to main content</a><nav class="nav"><ul class="navigation" id="navigation"><li class="navigation-item-emoji navigation-item-home"><a class="navigation-anchor" href="/Front-end-Developer-Interview-Questions/" title="Home"><em>★</em><span>Front-end Developer Interview Questions</span></a></li><li class="navigation-item-emoji navigation-item-translations"><a class="navigation-anchor" href="/Front-end-Developer-Interview-Questions/translations" title="Translations"><em>🌐</em><span>Translations</span></a></li><li class="navigation-item navigation-questions-label"><button class="navigation-toggle" id="navigation-toggle">Questions:</button></li><li class="navigation-item navigation-questions"><ul class="navigation navigation-questions-list"><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/general-questions/" title="General Questions">General</a></li><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/html-questions/" title="HTML Questions">HTML</a></li><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/css-questions/" title="CSS Questions">CSS</a></li><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/javascript-questions/" title="JavaScript Questions">JavaScript</a></li><li class="navigation-item"><a rel="external noreferrer noopener" target="_blank" class="navigation-anchor navigation-questions-anchor" href="https://scottaohara.github.io/accessibility_interview_questions/" title="Accessibility Questions (external link)">A11y</a></li><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/testing-questions/" title="Testing Questions">Testing</a></li><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/performance-questions/" title="Performance Questions">Performance</a></li><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/network-questions/" title="Network Questions">Network</a></li><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/coding-questions/" title="Coding Questions">Coding</a></li><li class="navigation-item"><a class="navigation-anchor navigation-questions-anchor" href="/Front-end-Developer-Interview-Questions/questions/fun-questions/" title="Fun Questions">Fun</a></li></ul></li></ul></nav><main id="main-content" tabindex="-1"><header class="header"><h1 class="header-big-title">Front End Developer Interview Questions</h1></header><div class="content"><h2 id="table-of-contents" tabindex="-1"><a class="header-anchor" href="#table-of-contents"></a> <a name="toc">Table of Contents</a></h2><ol><li><a href="#general">General Questions</a></li><li><a href="#html">HTML Questions</a></li><li><a href="#css">CSS Questions</a></li><li><a href="#js">JS Questions</a></li><li><a href="#testing">Testing Questions</a></li><li><a href="#performance">Performance Questions</a></li><li><a href="#network">Network Questions</a></li><li><a href="#fun">Fun Questions</a></li></ol><h4><a href="#toc">[⬆]</a> <a name="general">General Questions:</a></h4><ul><li>What did you learn yesterday/this week?</li><li>What excites or interests you about coding?</li><li>What is a recent technical challenge you experienced and how did you solve it?</li><li>When building a new web site or maintaining one, can you explain some techniques you have used to increase performance?</li><li>Can you describe some SEO best practices or techniques you have used lately?</li><li>Can you explain any common techniques or recent issues solved in regards to front-end security?</li><li>What actions have you personally taken on recent projects to increase maintainability of your code?</li><li>Talk about your preferred development environment.</li><li>Which version control systems are you familiar with?</li><li>Can you describe your workflow when you create a web page?</li><li>If you have 5 different stylesheets, how would you best integrate them into the site?</li><li>Can you describe the difference between progressive enhancement and graceful degradation?</li><li>How would you optimize a website’s assets/resources?</li><li>How many resources will a browser download from a given domain at a time?<ul><li>What are the exceptions?</li></ul></li><li>Name 3 ways to decrease page load (perceived or actual load time).</li><li>If you jumped on a project and they used tabs and you used spaces, what would you do?</li><li>Describe how you would create a simple slideshow page.</li><li>If you could master one technology this year, what would it be?</li><li>Explain the importance of standards and standards bodies.</li><li>What is Flash of Unstyled Content? How do you avoid FOUC?</li><li>Explain what ARIA and screenreaders are, and how to make a website accessible.</li><li>Explain some of the pros and cons for CSS animations versus JavaScript animations.</li><li>What does CORS stand for and what issue does it address?</li><li>How did you handle a disagreement with your boss or your collaborator?</li><li>What resources do you use to learn about the latest in front end development and design?</li><li>What skills are needed to be a good front-end developer?</li><li>What role do you see yourself in?</li><li>Explain the difference between cookies, session storage, and local storage?</li><li>Can you explain what happens when you enter a URL into the browser?</li><li>Describe the difference between SSR and CSR. Discuss the pros and cons.<ul><li>Are you familiar with static rendering?</li><li>Rehydration?</li></ul></li></ul><h4><a href="#toc">[⬆]</a> <a name="html">HTML Questions:</a></h4><ul><li>What does a <code>doctype</code> do?</li><li>How do you serve a page with content in multiple languages?</li><li>What kind of things must you be wary of when designing or developing for multilingual sites?</li><li>What are <code>data-</code> attributes good for?</li><li>Consider HTML5 as an open web platform. What are the building blocks of HTML5?</li><li>Describe the difference between a <code>cookie</code>, <code>sessionStorage</code> and <code>localStorage</code>.</li><li>Describe the difference between <code><script></code>, <code><script async></code> and <code><script defer></code>.</li><li>Why is it generally a good idea to position CSS <code><link></code>s between <code><head></head></code> and JS <code><script></code>s just before <code></body></code>? Do you know any exceptions?</li><li>What is progressive rendering?</li><li>Why you would use a <code>srcset</code> attribute in an image tag? Explain the process the browser uses when evaluating the content of this attribute.</li><li>Have you used different HTML templating languages before?</li><li>What is the difference between <code>canvas</code> and <code>svg</code>?</li><li>What are empty elements in HTML ?</li></ul><h4><a href="#toc">[⬆]</a> <a name="css">CSS Questions:</a></h4><ul><li>What is CSS selector specificity and how does it work?</li><li>What is the difference between “resetting” and “normalizing” CSS? Which would you choose, and why?</li><li>Describe Floats and how they work.</li><li>Describe z-index and how stacking context is formed.</li><li>Describe BFC (Block Formatting Context) and how it works.</li><li>What are the various clearing techniques and which is appropriate for what context?</li><li>How would you approach fixing browser-specific styling issues?</li><li>How do you serve your pages for feature-constrained browsers?<ul><li>What techniques/processes do you use?</li></ul></li><li>What are the different ways to visually hide content (and make it available only for screen readers)?</li><li>Have you ever used a grid system, and if so, what do you prefer?</li><li>Have you used or implemented media queries or mobile specific layouts/CSS?</li><li>Are you familiar with styling SVG?</li><li>Can you give an example of an <code>@media</code> property other than <code>screen</code>?</li><li>What are some of the “gotchas” for writing efficient CSS?</li><li>What are the advantages/disadvantages of using CSS preprocessors?<ul><li>Describe what you like and dislike about the CSS preprocessors you have used.</li></ul></li><li>How would you implement a web design comp that uses non-standard fonts?</li><li>Explain how a browser determines what elements match a CSS selector.</li><li>Describe pseudo-elements and discuss what they are used for.</li><li>Explain your understanding of the box model and how you would tell the browser in CSS to render your layout in different box models.</li><li>What does <code>* { box-sizing: border-box; }</code> do? What are its advantages?</li><li>What is the CSS <code>display</code> property and can you give a few examples of its use?</li><li>What is the difference between inline and inline-block?</li><li>What is the difference between the “nth-of-type()” and “nth-child()” selectors?</li><li>What is the difference between a relative, fixed, absolute and statically positioned element?</li><li>What existing CSS frameworks have you used locally, or in production? How would you change/improve them?</li><li>Have you used CSS Grid?</li><li>Can you explain the difference between coding a web site to be responsive versus using a mobile-first strategy?</li><li>Have you ever worked with retina graphics? If so, when and what techniques did you use?</li><li>Is there any reason you’d want to use <code>translate()</code> instead of <em>absolute positioning</em>, or vice-versa? And why?</li><li>How is clearfix css property useful?</li><li>Can you explain the difference between px, em and rem as they relate to font sizing?</li><li>Can you give an example of a pseudo class? Can you provide an example use case for a pseudo class?</li><li>What is the difference between a block level element and an inline element. Can you provide examples of each type of element?</li><li>What is the difference between CSS Grid and Flexbox? When would you use one over the other?</li><li>What is the difference between fixed, fluid and responsive layouts?</li></ul><h4><a href="#toc">[⬆]</a> <a name="js">JS Questions:</a></h4><ul><li>Explain event delegation.</li><li>Explain how <code>this</code> works in JavaScript.<ul><li>Can you give an example of one of the ways that working with <code>this</code> has changed in ES6?</li></ul></li><li>Explain how prototypal inheritance works.</li><li>What is the difference between a variable that is: <code>null</code>, <code>undefined</code> or undeclared?<ul><li>How would you go about checking for any of these states?</li></ul></li><li>What is a closure, and how/why would you use one?</li><li>What language constructions do you use for iterating over object properties and array items?</li><li>Can you describe the main difference between the <code>Array.forEach()</code> loop and <code>Array.map()</code> methods and why you would pick one versus the other?</li><li>What is a typical use case for anonymous functions?</li><li>What is the difference between host objects and native objects?</li><li>Explain the difference between: <code>function Person(){}</code>, <code>var person = Person()</code>, and <code>var person = new Person()</code>?</li><li>Explain the differences on the usage of <code>foo</code> between <code>function foo() {}</code> and <code>var foo = function() {}</code></li><li>Can you explain what <code>Function.call</code> and <code>Function.apply</code> do? What is the notable difference between the two?</li><li>Explain <code>Function.prototype.bind</code>.</li><li>What is the difference between feature detection, feature inference, and using the UA string?</li><li>Explain “hoisting”.</li><li>What is type coercion? What are common pitfalls of relying on type coercion in JavaScript code?</li><li>Describe event bubbling.</li><li>Describe event capturing.</li><li>What is the difference between an “attribute” and a “property”?</li><li>What are the pros and cons of extending built-in JavaScript objects?</li><li>What is the difference between <code>==</code> and <code>===</code>?</li><li>Explain the same-origin policy with regards to JavaScript.</li><li>Why is it called a Ternary operator, what does the word “Ternary” indicate?</li><li>What is strict mode? What are some of the advantages/disadvantages of using it?</li><li>What are some of the advantages/disadvantages of writing JavaScript code in a language that compiles to JavaScript?</li><li>What tools and techniques do you use debugging JavaScript code?</li><li>Explain the difference between mutable and immutable objects.<ul><li>What is an example of an immutable object in JavaScript?</li><li>What are the pros and cons of immutability?</li><li>How can you achieve immutability in your own code?</li></ul></li><li>Explain the difference between synchronous and asynchronous functions.</li><li>What is event loop?<ul><li>What is the difference between call stack and task queue?</li></ul></li><li>What are the differences between variables created using <code>let</code>, <code>var</code> or <code>const</code>?</li><li>What are the differences between ES6 class and ES5 function constructors?</li><li>Can you offer a use case for the new arrow <code>=></code> function syntax? How does this new syntax differ from other functions?</li><li>What advantage is there for using the arrow syntax for a method in a constructor?</li><li>What is the definition of a higher-order function?</li><li>Can you give an example for destructuring an object or an array?</li><li>Can you give an example of generating a string with ES6 Template Literals?</li><li>Can you give an example of a curry function and why this syntax offers an advantage?</li><li>What are the benefits of using <code>spread syntax</code> and how is it different from <code>rest syntax</code>?</li><li>How can you share code between files?</li><li>Why you might want to create static class members?</li><li>What is the difference between <code>while</code> and <code>do-while</code> loops in JavaScript?</li><li>What is a promise? Where and how would you use promise?</li><li>Discuss how you might use Object Oriented Programming principles when coding with JavaScript.</li></ul><h4><a href="#toc">[⬆]</a> <a name="code-questions">Coding Questions:</a></h4><ul><li>Make this work:</li></ul><pre class="language-javascript"><code class="language-javascript"><span class="token function">duplicate</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// [1,2,3,4,5,1,2,3,4,5]</span></code></pre><ul><li>Create a for loop that iterates up to <code>100</code> while outputting <strong>“fizz”</strong> at multiples of <code>3</code>, <strong>“buzz”</strong> at multiples of <code>5</code> and <strong>“fizzbuzz”</strong> at multiples of <code>3</code> and <code>5</code></li><li>What will be returned by each of these?</li></ul><pre class="language-javascript"><code class="language-javascript">console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">"hello"</span> <span class="token operator">||</span> <span class="token string">"world"</span><span class="token punctuation">)</span>
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||
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">"foo"</span> <span class="token operator">&&</span> <span class="token string">"bar"</span><span class="token punctuation">)</span></code></pre><ul><li>Write an immediately invoked function expression (IIFE)</li></ul><h4><a href="#toc">[⬆]</a> <a name="testing">Testing Questions:</a></h4><ul><li>What are some advantages/disadvantages to testing your code?</li><li>What tools would you use to test your code’s functionality?</li><li>What is the difference between a unit test and a functional/integration test?</li><li>What is the purpose of a code style linting tool?</li><li>What are some of the testing best practices?</li></ul><h4><a href="#toc">[⬆]</a> <a name="performance">Performance Questions:</a></h4><ul><li>What tools would you use to find a performance bug in your code?</li><li>What are some ways you may improve your website’s scrolling performance?</li><li>Explain the difference between layout, painting and compositing.</li></ul><h4><a href="#toc">[⬆]</a> <a name="network">Network Questions:</a></h4><ul><li>Traditionally, why has it been better to serve site assets from multiple domains?</li><li>Do your best to describe the process from the time you type in a website’s URL to it finishing loading on your screen.</li><li>What are the differences between Long-Polling, Websockets and Server-Sent Events?</li><li>Explain the following request and response headers:<ul><li>Diff. between Expires, Date, Age and If-Modified-…</li><li>Do Not Track</li><li>Cache-Control</li><li>Transfer-Encoding</li><li>ETag</li><li>X-Frame-Options</li></ul></li><li>What are HTTP methods? List all HTTP methods that you know, and explain them.</li><li>What is domain pre-fetching and how does it help with performance?</li><li>What is a CDN and what is the benefit of using one?</li></ul><h4><a href="#toc">[⬆]</a> <a name="fun">Fun Questions:</a></h4><ul><li>What is a cool project that you’ve recently worked on?</li><li>What are some things you like about the developer tools you use?</li><li>Who inspires you in the front-end community?</li><li>Do you have any pet projects? What kind?</li></ul></div><div class="content-edit"><a rel="external noreferrer noopener" target="_blank" href="https://github.com/h5bp/Front-end-Developer-Interview-Questions/tree/master/src/translations/************.md">Edit this page</a></div></main><footer class="footer"><p class="footer-text">Copyright © 2012 - 2024. Contributors to <a href="https://github.com/h5bp/Front-end-Developer-Interview-Questions/blob/main/CONTRIBUTORS.md">Front-end-Developer-Interview-Questions.</a><br>Curious about the project? <a href="/Front-end-Developer-Interview-Questions/about/">Read more about here</a>.</p></footer></div><script>console.log("%cA black belt is a white belt that didn't quit.","color: #fff; font-size: 20px; text-shadow: 1px 1px 1px #000; font-family: serif;");var navToggle=document.getElementById("navigation-toggle"),nav=document.getElementById("navigation");navToggle.addEventListener("click",function(){nav.classList.toggle("open")}),window.addEventListener("resize",function(){document.width>960?nav.classList.remove("active"):(nav.classList.add("no-motion"),setTimeout(function(){nav.classList.remove("no-motion")},250))});</script></body></html> |