web-developer-interview-questions.md

Web Developer Common Interview Questions:

HTML / CSS / JavaScript / DevTool

• What is the importance of Doctype in HTML?
• What is the difference between display: none and visibility: hidden?
• Consider the following code: What font-size will have the text inside the

  element?

  <div> Lorem ipsum
    <p> Lorem ipsum</p>
  </div>

    div {
      font-size: 16px;
    }
    p {
      font-size: 0.5em;
    }

• What is the difference between sessionStorage and localStorage?
• What are data-attributes?
• Explain the difference between Normalize CSS and Reset CSS?
• What are sprites, what is their purpose?
• What is SVG?
• What are the new features of HTML5 standard?
• What is a CSS preprocessor?
• What is microdata?
• What tags are used to make a table?
• What is the CSS Box Model?
• What is priority order of CSS selectors?
• What is the reason for wrapping the entire content of a JavaScript source file in a function?
• How would you inspect a hover state of an element in the devtools?
• What is the difference between "==" and "===" operators in JavaScript?
• What kinds of loops are in JavaScript?
• What is anti-pattern?

Performance Questions:

• What tools would you use to find a performance bug in your code?

• DevTools in browsers such as Firefox and Chrome provides decent tools for your to debug and improve website performance.
• Dynatrace

• Quora: What are the tools used for finding bugs in web applications websites

• Open Classroom: Optimize your website with DevTools

• What are some ways you may improve your website's scrolling performance?

• Explain the difference between layout, painting and compositing.

Network Questions:

• Traditionally, why has it been better to serve site assets from multiple domains?
• Do your best to describe the process from the time you type in a website's URL to it finishing loading on your screen.
• What are the differences between Long-Polling, Websockets and Server-Sent Events?
• Explain the following request and response headers:
  • Diff. between Expires, Date, Age and If-Modified-...
  • Do Not Track
  • Cache-Control
  • Transfer-Encoding
  • ETag
  • X-Frame-Options
• What are HTTP methods? List all HTTP methods that you know, and explain them.

Testing Questions:

• What are some advantages/disadvantages to testing your code?
• What tools would you use to test your code's functionality?
• What is the difference between a unit test and a functional/integration test?
• What is the purpose of a code style linting tool?

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