Are you ready to take your web development skills to the next level and land that dream job in the tech world? Well, you’ve come to the right place! We’ve compiled the ultimate cheat sheet for your HTML, CSS, and JavaScript interviews. In this article, we’ll explore the top 40+ HTML CSS JavaScript interview questions and answers.
Whether you’re a fresher or an experienced developer, we’ve got you covered.
HTML CSS JavaScript Interview Questions for Freshers
Here are some of the most important HTML CSS JavaScript interview questions and answers for freshers:
HTML Interview Questions and Answers
- What is HTML, and what does it stand for?
HTML stands for HyperText Markup Language. It’s a standard markup language used to create web pages.
- What is the basic structure of an HTML document?
An HTML document typically starts with <!DOCTYPE html> and contains <html>, <head>, and <body> tags.
- What are HTML elements and tags?
HTML elements are the building blocks of web pages, and tags are used to define and format elements. For example, <p> defines a paragraph.
- Explain the difference between <div> and <span> elements.
<div> is a block-level element used for grouping content, while <span> is an inline-level element used to apply styles to a portion of text.
- What is the purpose of the HTML id and class attributes?
The id attribute is used to uniquely identify an element, while the class attribute is used to group elements that share a common styling or behaviour.
CSS Interview Questions and Answers
- What does CSS stand for, and why is it important in web development?
CSS stands for Cascading Style Sheets. It’s crucial for controlling the presentation and layout of web pages, making them visually appealing.
- How do you link an external CSS file to an HTML document?
You can link an external CSS file using the <link> element in the HTML document’s <head> section.
- Explain the difference between padding and margin in CSS.
Padding is the space inside an element, while margin is the space outside of it. Padding affects the content area, while the margin affects the element’s positioning in the layout.
- What is the difference between the class and id selectors in CSS?
A class selector is used to target multiple elements with the same class, while an id selector targets a unique element. You can use a class on multiple elements, but an id should be unique.
- How do you centre an element horizontally in CSS?
To centre an element horizontally, you can set its margin to auto and specify a width.
JavaScript Interview Questions and Answers
- What is JavaScript, and how is it different from HTML and CSS?
JavaScript is a programming language used for adding interactivity and dynamic behaviour to web pages, while HTML is for structure and CSS is for styling.
- How do you declare a variable in JavaScript?
You can declare a variable using var, let, or const. For example, let myVar = 5.
- Explain the difference between null and undefined in JavaScript.
Null represents an intentional absence of any object value, while undefined signifies a variable that has been declared but hasn’t been assigned a value.
- What is a function in JavaScript, and how do you define one?
A function is a reusable block of code. You can define one using the function keyword, for example, function myFunction() { … }.
- How do you add an event listener to an HTML element in JavaScript?
You can use the addEventListener method to attach an event listener to an element. For example, element.addEventListener(‘click’, myFunction);.
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HTML CSS JavaScript Interview Questions for Experienced
Here are some of the most important HTML CSS JS interview questions and answers for freshers:
HTML Interview Questions and Answers
- Explain the purpose and usage of HTML5 semantic elements.
HTML5 introduced semantic elements like <header>, <nav>, and <section. They provide better structure and help improve accessibility and SEO.
- What is the significance of the data – attribute in HTML?
The data- attribute is used to store custom data private to the page or application. It’s often used for JavaScript to access data associated with an element.
- How does the <iframe> tag work, and what are its common use cases?
<iframe> is used to embed content from another source within a web page. Common uses include embedding video maps or displaying external content.
- What are the differences between HTML and XHTML?
XHTML is a stricter, XML-based version of HTML. It enforces well-formedness, uses lowercase tags, and requires all elements to be properly nested and closed.
- Explain the purpose of the aria-* attributes in HTML and their role in web accessibility.
aria-* attributes provide accessibility information to assistive technologies. They help make web content more accessible to people with disabilities.
CSS Interview Questions and Answers
- What is the CSS Box Model, and how does it affect layout?
The CSS Box Model defines how elements are rendered in terms of content, padding, border, and margin. Understanding it is crucial for precise layout control.
- Describe the CSS Flexbox and CSS Grid layout models and their use cases.
Flexbox is for one-dimensional layouts, like navigation bars. CSS Grid is for two-dimensional layouts, such as grids and complex page structures.
- What are CSS pre-processors, and why are they used?
CSS pre-processors like SASS and LESS extend CSS with variables, nesting, and functions, making stylesheets more maintainable and reusable.
- Explain the concept of specificity in CSS.
Specificity determines which CSS rule is applied when there are conflicting rules. It’s calculated based on selectors and the importance of selectors.
- What is a responsive web design, and how do media queries contribute to it?
Responsive web design is the practice of designing web pages that adapt to different screen sizes. Media queries allow CSS to apply different styles based on screen characteristics like width.
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JavaScript Interview Questions and Answers
- What are closures in JavaScript, and why are they useful?
Closures are functions that have access to their own scope and the outer function’s scope. They’re valuable for encapsulation and maintaining state.
- Explain the differences between let, const, and var for variable declaration.
let and const have block-level scope and are preferred over var. const is for constant values, while let is for variables that can be reassigned.
- What is the event delegation in JavaScript, and why is it advantageous?
Event delegation involves attaching a single event listener to a common ancestor instead of individual elements. It’s efficient for handling events on dynamically created or numerous elements.
- How does asynchronous programming work in JavaScript, and what are Promises and async/await?
Asynchronous programming in JavaScript is achieved using callbacks, Promises, and async/await. Promises represent a future value, and async/await simplifies asynchronous code.
- Explain the concept of the “this” keyword in JavaScript and how it behaves in different contexts.
“this” refers to the current object or context in JavaScript. Its value can vary in different contexts like global, object methods, and event handlers. Understanding “this” behaviour is essential for writing reliable code.
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HTML CSS JavaScript Viva Questions
Here are some of the most important HTML CSS JavaScript viva questions and answers:
HTML Viva Questions and Answers
- What is the difference between HTML and HTML5?
HTML is the standard markup language used to create web pages, while HTML5 is the latest version of HTML with new features like semantic elements, native multimedia support, and improved form controls.
- What is the purpose of the HTML5 <video> element?
The <video> element is used to embed video content directly into an HTML document, allowing users to play video files directly within the browser without the need for third-party plugins.
- How do you embed an image in an HTML document?
To embed an image in an HTML document, you use the <img> element with the src attribute specifying the URL of the image file.
CSS Viva Questions and Answers
- Explain the difference between inline and block elements in CSS.
Inline elements do not start on a new line and only occupy as much width as necessary, while block elements start on a new line and occupy the full width available.
- What is the CSS float property used for?
The CSS float property is used to specify whether an element should be floated to the left or right within its containing element. This property is commonly used for creating layouts where elements float next to each other, such as in navigation menus or multi-column layouts.
- What is the purpose of the z-index property in CSS?
The z-index property determines the stacking order of elements along the z-axis (depth) on the webpage. Elements with a higher z-index value will appear above elements with a lower value.
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JavaScript Viva Questions and Answers
- What is the role of JavaScript in web development?
JavaScript is a scripting language used for adding interactivity and dynamic behaviour to web pages. It allows for client-side scripting, handling user interactions, and manipulating HTML and CSS.
- What is the purpose of the JavaScript type of operator?
The type of operator is used to determine the data type of a variable or expression. It returns a string indicating the data type, such as “number”, “string”, “boolean”, “object”, “function”, or “undefined”.
- How do you handle errors in JavaScript?
Errors in JavaScript can be handled using try…catch blocks. Code that may throw an error is placed within the try block, and if an error occurs, it is caught and handled in the catch block. Additionally, you can use the throw statement to manually throw an error.
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HTML CSS JavaScript Multiple Choice Questions and Answers
This section includes multiple-choice questions (MCQs) to help you quickly review key concepts in HTML, CSS, and JavaScript. These questions are designed to challenge your understanding and prepare you for real interview scenarios.
- Which of the following is not a valid HTML tag?
- A) <article>
- B) <header>
- C) <navigate>
- D) <section>
Answer: C) <navigate>
- What does the alt attribute in the <img> tag specify?
- A) The file path of the image
- B) The title of the image
- C) Alternate text for the image
- D) The width of the image
Answer: C) Alternate text for the image
- Which CSS property is used to change the text color of an element?
- A) font-color
- B) color
- C) text-color
- D) text-style
Answer: B) color
- In CSS, how do you select an element with an id of “header”?
- A) .header
- B) #header
- C) header
- D) *header
Answer: B) #header
- Which JavaScript method is used to write content into an HTML document?
- A) document.write()
- B) console.log()
- C) window.alert()
- D) document.log()
Answer: A) document.write()
- How can you add a comment in a JavaScript file?
- A) <!– Comment –>
- B) // Comment
- C) /* Comment */
- D) Both B and C
Answer: D) Both B and C
- What does the CSS z-index property control?
- A) Opacity of an element
- B) Visibility of an element
- C) Position of an element along the z-axis
- D) Alignment of text in an element
Answer: C) Position of an element along the z-axis
- Which of the following is a correct way to declare a function in JavaScript?
- A) function: myFunction() {}
- B) function = myFunction() {}
- C) function myFunction() {}
- D) myFunction function() {}
Answer: C) function myFunction() {}
- What is the default display value of a <div> element in HTML?
- A) inline
- B) block
- C) flex
- D) grid
Answer: B) block
- Which property in CSS is used to make the text bold?
- A) font-weight
- B) font-style
- C) text-decoration
- D) text-transform
Answer: A) font-weight
Why Should You Learn HTML CSS and JavaScript Interview Questions?
Here are some reasons why you need to know interview questions on HTML CSS JavaScript:
- It will help you to impress your employers
- You can easily answer technical questions
- It will give you a competitive edge in the crowded job market
- It will open doors to higher-paying roles in web development
- You can easily ace your job interview
- It will help ease interview anxiety
Conclusion
Learning these top 40+ HTML CSS and JavaScript interview questions gives you with essential skills to ace web development job interviews. If you’re looking for front-end developer job opportunities, look no further than Hirist. It is the number one online platform to find IT jobs. Your dream job awaits – start your journey with Hirist today!
