10 most important front-end developer interview questions and answers

You've probably noticed a declaration before the tag in an HTML page. The element in HTML is used to tell the browser what version of HTML is being used in the page. This document type declaration is called (DTD).

The doctype declaration varies depending on the HTML version.

Session Storage: As the name implies, this data is saved until the session or tab is closed; however, it is not removed when the browser is reloaded. This information is kept on the client-side and cannot be sent to the server.

LocalStorage: This data is kept locally on the client's machine. This data has no expiration date; however, it is restricted to string data only. You can use Javascript and HTML to access local data, but you cannot send them to the server. Although data in local storage has no expiration date, the user can choose to delete it.

Cookies: Cookies transmitted back to the server must be less than 4KB in size. When a further XHR request is performed, the data is returned. Although they are intended for server-side reading, they can also be accessed from the client.

Either getElementById or querySelector may be used to obtain a DOM node. Then, by calling .childNodes you may receive all of its children (note: childNodes does not return an Array, but a NodeList). To traverse the DOM, you can iterate through the childNodes by calling childNodes on each one of them. You may retrace your steps by looking at the parentNode of any node.

Some significant disadvantages of using CSS preprocessors are:

• Compilation times may take longer than expected. This is because you must translate every SASS file to CSS before building it.
• Because it combines several CSS files, the primary file might get rather huge. This increases the time it takes to execute a request.
• There is a longer learning curve since the user must have a thorough grasp of the preprocessor before using it.

Synchronous methods: Synchronous functions prevent the application from running until the file operation is completed. Blocking functions is another name for these functions. The last argument in synchronous methods is File Descriptor. A file descriptor is a reference to files that have been opened. It's a number or a file reference id returned after using the fs module's fs.open() function to open the file. By putting "Sync" to the function name, all asynchronous methods may be made to run synchronously.

Asynchronous functions do not stall the program's execution, and each instruction is performed after the one before it, even if the prior command hasn't computed the result. The preceding command keeps running in the background until it is complete and then loads the result. As a result, these functions are referred to as non-blocking functions. The last parameter expected is a callback function. Asynchronous functions are often favored over synchronous functions because they do not prevent the program from running until it has completed processing, whereas synchronous functions do.

Load balancing is a way of allocating and processing requests across several devices rather than a single device. This guarantees that the load is distributed efficiently and does not rely on a single location.

Round Robin is the most often utilized load balancing technique. The requests are dispersed over a collection of servers in this approach. The algorithm distributes requests to the servers and then returns to the top to restart the process.

The right use of HTML to reinforce the meaning of material on a web page, rather than only specify its look, is known as semantic HTML.

Search engines, screen readers, and other user devices can employ semantically valid HTML to assess the importance and context of web content. Appropriate HTML components are chosen based on their intrinsic meaning rather than how they seem aesthetically on a produced web page in order to reflect the essence of information effectively.

• Using server-side rendering, we can construct a unique stylesheet for each browser.
• Another option is to use a package such as Bootstrap, which already contains the code to deal with the browser-specific styling problem.
• Reset and Normalize CSS are also options.
• Many third-party plugins include libraries to help with browser style.

When one element's layout, window size, or other properties are altered, the position of all subsequent elements changes as well. This, in turn, impacts the page's flow, which is referred to as reflow.

You may avoid reflow by using the following methods:

• It's best to avoid using several inline styles.
• Avoid using tables in your design.
• Only use animations on fixed or absolute items.

No, window.onload and document.onload are not fired simultaneously. When the DOM is ready, Document.onload is called. This can happen before or after the pictures, scripts, and other information have been loaded.

Window.onload, on the other hand, is only invoked after the DOM is fully loaded and ready with all content, including images, scripts, and CSS.