Amazon Interview Questions and Answers

Javascript is single threaded.

• Javascript has a single call stack and event loop.

• It can handle asynchronous operations through callbacks and promises.

• Web workers can be used for multi-threading in Javascript.

Prototype is a property of an object that allows adding new properties and methods to an existing object.

• Prototype is a blueprint for creating objects.

• It is used to add new properties and methods to an existing object.

• All objects in JavaScript have a prototype property.

• The prototype property is used to share properties and methods between objects.

• Modifying the prototype of an object affects all instances of that object.

Reverse array, get substring, remove 0s

• Use array.reverse() to reverse the array

• Use string.substring() to get a substring

• Use array.filter() to remove 0s from the array

Event loop is a mechanism that allows JavaScript to perform non-blocking I/O operations.

• Event loop is a part of JavaScript runtime that continuously checks the call stack and the task queue.

• It executes the tasks in the task queue one by one, and once the task is completed, it is removed from the queue.

• Event loop ensures that the JavaScript code does not block the main thread and allows for asynchronous programming.

• Examples of asynchronous operations that use event loop are se...read more

Virtual DOM is a lightweight copy of the actual DOM that allows for efficient updates and rendering in web applications.

• Virtual DOM is a concept used in frameworks like React to improve performance by minimizing direct manipulation of the actual DOM.

• When changes are made to the virtual DOM, a comparison is done with the actual DOM to identify the minimal updates needed, reducing re-renders.

• This approach helps in optimizing rendering speed and improving user experience in web ...read more