Divami Design Labs Interview Questions and Answers

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.

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var is function-scoped while let is block-scoped.

• var declarations are hoisted to the top of their scope while let declarations are not.

• var can be redeclared in the same scope while let cannot.

• let is preferred over var for better code readability and avoiding unexpected behavior.

• Example: var x = 10; if (true) { var x = 20; } console.log(x); // Output: 20 let y = 10; if (true) { let y = 20; } console.log(y

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

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.