10+ Deloitte Front end Developer Interview Questions and Answers

Data can be passed in components using props in Vue.js and React.js.

• In Vue.js, data can be passed down to child components using props.

• In React.js, data can be passed down to child components using props as well.

• In Vue.js, props are defined in the parent component and passed down to the child component.

• In React.js, props are passed down from parent to child components as attributes.

Use infinite scrolling to fetch new content as user scrolls down the page.

• Implement infinite scrolling to load more products as user scrolls down

• Make AJAX calls to fetch new content from the server

• Update the DOM with the new content dynamically

The output will display the document object in the console.

• Typing 'document' in the console will return the document object, which represents the current HTML document.

• The document object provides access to the content and structure of the webpage, allowing manipulation of elements and properties.

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

• Variable declarations are hoisted but not their initializations.

• Function declarations are fully hoisted.

• Example: console.log(myVar); var myVar = 10; // Output: undefined

• Example: console.log(myFunc()); function myFunc() { return 'Hello!'; } // Output: Hello!

Semantic elements in HTML provide meaning to the content, making it easier for search engines and screen readers to interpret.

• Semantic elements are HTML tags that clearly define the content they wrap.

• They provide structure and meaning to the content, making it more accessible and SEO-friendly.

• Examples include <header>, <footer>, <nav>, <article>, <section>, <aside>, <main>, <figure>, <figcaption>.

Data can be shared between components in React using props, context, or state management libraries like Redux.

• Use props to pass data from parent to child components

• Use context to share data across multiple components without passing props manually

• Use state management libraries like Redux to manage global state and share data between components

Closures are functions that have access to their own scope, as well as the scope in which they were defined.

• Closures allow functions to access variables from their outer function even after the outer function has finished executing.

• Closures are commonly used in event handlers and callbacks.

• Example: function outerFunction() { let outerVar = 'I am outer'; return function innerFunction() { console.log(outerVar); }; }

DOM stands for Document Object Model, it is a programming interface for web documents. It represents the structure of a document as a tree of objects.

• DOM is used to interact with HTML and XML documents in a structured way

• It allows developers to manipulate the content, structure, and style of a website dynamically

• DOM provides methods and properties to access and modify elements on a web page

• Example: document.getElementById('myElement') allows you to access an element with a sp...read more

Using map function to apply a callback function to each element in an array

• Map function is used to iterate over an array and apply a callback function to each element

• The callback function can perform operations on each element and return a new value

• Example: arr.map(item => item * 2) will double each element in the array

Error handling in JavaScript involves using try-catch blocks, throwing custom errors, and using error objects.

• Use try-catch blocks to catch and handle errors

• Throw custom errors using the throw keyword

• Use error objects like Error, SyntaxError, TypeError, etc. for specific types of errors

Flexbox is best for one-dimensional layouts, Grid is best for two-dimensional layouts, DOM is the structure of a webpage, Box model is the layout of elements.

• Flexbox is best for creating one-dimensional layouts like navigation bars or sidebars.

• Grid is best for creating two-dimensional layouts like grids of images or cards.

• DOM (Document Object Model) is the structure of a webpage, representing the elements as objects.

• Box model defines how elements are laid out on a webpage, in...read more

HTML5 is the latest version of HTML with new features and improvements.

• HTML5 supports new elements like <header>, <footer>, <nav>, <article>, <section> etc.

• HTML5 supports new input types like email, url, date, range, color etc.

• HTML5 supports new APIs like Geolocation, Web Storage, Web Workers, Canvas, Audio/Video etc.

Prop drilling is the process of passing data through multiple levels of components in React.

• Prop drilling occurs when a component needs to pass data to a deeply nested child component.

• It can lead to code that is hard to maintain and understand.

• One way to avoid prop drilling is by using Context API or Redux for state management.

Redux is a predictable state container for JavaScript apps.

• Redux stores the entire state of an application in a single immutable object.

• State changes are made by dispatching actions, which are plain JavaScript objects.

• Reducers specify how the application's state changes in response to actions.

• Redux flow: Action -> Reducer -> Store -> View