MERN stands for MongoDB, Express, React, Node, after the four key technologies that make up the stack.
Q11. What is the purpose of meta tags?
The META elements can be used to include name/value pairs describing properties of the HTML document, such as author, expiry date, a list of keywords, document author etc.
<meta name=”author” content=”Author Name”>
Q12. Does localStorage throw error after reaches maximum limits?
Yes, localStorage throw error after reaches maximum limits.
Q13. Can a web page contain multiple <header> elements and What about <footer> elements?
Yes, header elements can be used multiple times in documents. A <header> tag must be present for all articles, sections, and pages, although a <footer> tag is not necessary.
Q14. Describe the difference between a cookie, sessionStorage and localStorage?
Cookie: A text file saved on the users computer to store and retrieve data
sessionStorage: Is memory space in a browser to save temporary data until the window or tab is closed.
localStorage: Memory space in a browser to save permanently data until the window or tab is closed.
Q15. Explain Application Cache in HTML5. OR What is a manifest file in HTML?
HTML5 provides an application caching mechanism that lets web-based applications run offline.
Application cache gives an application the following benefits:
– Offline browsing
– Reduced server load
Note: Use Service Workers instead because it’s in the process of being removed from the Web platform.
Q16. What does async and defer refer in script tag? Describe the difference between <script>, <script async> and <script defer>?
Async: Downloads the script file during HTML parsing and will pause the HTML parser to execute it when it has finished downloading.
Defer: Downloads the script file during HTML parsing and will only execute it after the HTML parser has completed. Not all browsers support this.
Q17. What is the purpose of the alt attribute on images?
The alt attribute provides alternative information for an image if a user cannot view it.
<img src=”mountain.png” alt=”Mountains”>
Q18. What is Character Encoding?
Character encoding is a method of converting bytes into characters. To validate or display an HTML document properly, a program must choose a proper character encoding. This is specified in the tag:
Q19. Why to use IndexedDB instead of WebSQL in HTML5?
It is the successor to both LocalStorage and WebSQL, designed to replace them as the “one true” browser database. It exposes an asynchronous API that supposedly avoids blocking the DOM.
Q20. What ARIA and screenreaders are, and how to make a website accessible?
Screen readers are software programs that provide assistive technologies that allow people with disabilities to use web applications. You can make your sites more accessible by following ARIA standards such as semantic HTML, alt attributes and using [role=button] in the expected ways.