Fullstack Developer

You can cancel a scheduled timeout in JavaScript using the clearTimeout function. The setTimeout function returns a timer ID, which is a numeric value. The clearTimeout function takes this timer ID as an argument and cancels the execution of the corresponding timeout.

SELECT MAX(Salary) AS SecondHighestSalary
FROM Employees
WHERE Salary < (SELECT MAX(Salary) FROM Employees);

The event loop is the core mechanism in Node.js that enables asynchronous, non-blocking operations by continuously checking for events and executing associated callbacks. This allows Node.js to efficiently handle a large number of concurrent connections and perform I/O operations without blocking the execution of other code.

Callbacks, Promises, and async/await are all mechanisms in JavaScript for handling asynchronous operationscallbacks are the most basic form of handling asynchronous code, Promises provide a more structured and readable approach.async/await builds on top of Promises, offering a more synchronous-like syntax and improved error handling.

In React, the component lifecycle refers to the series of phases that a React component goes through from its creation to its removal from the DOM. Each phase in the lifecycle provides developers with specific hooks or methods to perform various tasks or respond to specific events. These lifecycle methods allow developers to control the behavior of a component at different points in its existence.Additionally, React introduced the concept of "side effects" in functional components using the useEffect hook. The useEffect hook can be used to perform side effects in functional components and is similar in purpose to componentDidMount, componentDidUpdate, and componentWillUnmount lifecycle methods.

JWTs provide a secure and compact way of transmitting information between parties. They are widely used for stateless authentication, allowing servers to verify and trust information provided by clients without the need for session storage. The integrity of the token is ensured through the use of a signature, and the payload can contain various claims about the user.