Larsen & Toubro Limited Interview Questions and Answers

JavaScript design patterns are reusable solutions to common problems in software design.

• Some common design patterns in JavaScript include Module, Singleton, Observer, Factory, and Prototype.

• Module pattern helps in creating encapsulated modules with private and public methods.

• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Observer pattern allows objects to subscribe and unsubscribe to events and be notified of changes.

• Factor...read more

A state in React is a JavaScript object that stores data relevant to a component and can be updated over time.

• State is initialized in a component's constructor using this.state = {}

• State can be updated using this.setState() method

• State changes trigger re-rendering of the component

Slice is a method that extracts a portion of an array without modifying the original array, while splice is a method that adds or removes elements from an array.

• Slice returns a shallow copy of a portion of an array based on start and end index parameters.

• Splice can add new elements to an array or remove existing elements by specifying the start index and number of elements to remove.

• Example: const arr = [1, 2, 3, 4, 5]; arr.slice(1, 3) will return [2, 3], while arr.splice(1, ...read more

Prototype chain in JavaScript is the mechanism by which objects inherit properties and methods from other objects.

• In JavaScript, each object has a private property which holds a link to another object called its prototype.

• If a property or method is not found on an object, JavaScript will look for it in the object's prototype, and so on up the chain.

• This allows for inheritance in JavaScript, where objects can inherit properties and methods from their prototypes.

React context is a built-in feature for passing data through the component tree, while React Redux is a library for managing global state in React applications.

• React context is used for passing data down the component tree without having to pass props manually at every level.

• React Redux is a library that provides a centralized store for managing global state in a React application.

• React context is built into React, while React Redux is a separate library that needs to be inst...read more

Closures are functions that have access to variables from their containing scope even after the function has finished executing.

• Closures allow functions to access variables from their outer scope

• They maintain a reference to the variables even after the outer function has finished executing

• Closures are commonly used in event handlers and callbacks