10+ MJS CO Interview Questions and Answers

This question is about finding the weight of the last stone after repeatedly smashing the two heaviest stones together.

• Sort the array of stone weights in descending order.

• Repeatedly smash the two heaviest stones until there is at most 1 stone left.

• If there is 1 stone left, return its weight. Otherwise, return 0.

Higher order functions are functions that can take other functions as arguments or return functions as their results.

• Higher order functions can be used to create more flexible and reusable code.

• They enable functional programming paradigms.

• Examples of higher order functions include map, filter, and reduce in JavaScript.

A todo list application using localstorage.

• Use HTML, CSS, and JavaScript to create the user interface.

• Use the localstorage API to store and retrieve todo items.

• Implement features like adding, editing, and deleting todo items.

• Display the list of todo items and their status.

• Allow users to mark todo items as completed or incomplete.

Hoisting is a JavaScript behavior where variable and function declarations are moved to the top of their containing scope.

• Hoisting applies to both variable and function declarations.

• Variable declarations are hoisted but not their initializations.

• Function declarations are fully hoisted, including their definitions.

• Hoisting can lead to unexpected behavior if not understood properly.

Promises in JavaScript are objects that represent the eventual completion or failure of an asynchronous operation.

• Promises are used to handle asynchronous operations such as fetching data from a server or reading a file.

• They simplify the process of writing asynchronous code by providing a more structured approach.

• Promises have three states: pending, fulfilled, or rejected.

• They can be chained together using methods like .then() and .catch().

• Promises help avoid callback hell an...read more

Design a signin page using HTML and CSS only

• Create a form element with input fields for username and password

• Style the form using CSS to make it visually appealing

• Add a submit button for users to sign in

• Consider adding error messages or validation for user input

• Use CSS to make the page responsive for different screen sizes

Memoization is a technique in JavaScript to cache the results of expensive function calls for future use.

• Memoization improves performance by avoiding redundant calculations

• It is commonly used in recursive functions or functions with expensive computations

• The cached results are stored in a data structure like an object or a map

• Memoization can be implemented manually or using libraries like Lodash or Memoizee

Temporal Dead Zone is a behavior in JavaScript where variables are not accessible before they are declared.

• Temporal Dead Zone occurs when accessing variables before they are declared

• Variables in the Temporal Dead Zone cannot be accessed or assigned

• The Temporal Dead Zone is a result of JavaScript's hoisting behavior

• Example: accessing a variable before it is declared will throw a ReferenceError

Arrow functions are a concise way to write functions in JavaScript.

• Arrow functions have a shorter syntax compared to regular functions.

• They do not have their own 'this' value.

• They do not have the 'arguments' object.

• They cannot be used as constructors with the 'new' keyword.

• They are commonly used in functional programming and with array methods like 'map' and 'filter'.

Virtual DOM is a lightweight copy of the actual DOM that allows efficient updates and rendering in JavaScript frameworks.

• Virtual DOM is a concept used in JavaScript frameworks like React.

• It is a lightweight copy of the actual DOM tree.

• Changes made to the virtual DOM are compared with the actual DOM to determine the minimal updates needed.

• This helps in efficient rendering and improves performance.

• Virtual DOM allows developers to write code as if the entire page is rendered on ...read more

IIFE stands for Immediately Invoked Function Expression. It is a JavaScript function that is executed as soon as it is defined.

• IIFE is a way to create a function expression and immediately invoke it.

• It helps in creating a private scope for variables and functions.

• It is commonly used to avoid polluting the global namespace.

• IIFE can be written using different syntaxes like using parentheses, function declaration, or arrow functions.