What is React —

React is a very popular small javascript library that builds user interfaces nowadays. its do very easy to make applications rather than row HTML, CSS, Javascript. and its more beautiful things is its Virtual DOM and Diffing Algorithm. there all make your app very efficient and faster.

Virtual Dom —

We all know DOM is a “Document Object Model”.who worked in the browser. Normally as we can see, when we interact on our site, the Dom is reloading everything in our site and it takes some time for rendering. that’s why it’s not very efficient. to solve this problem react can go a…


ES6 Special

Building Blocks:
To be good at JavaScript, every beginner should start with understanding its building blocks. Building blocks are the smallest part of a big thing.
So the building blocks of JavaScript are Number, String, Boolean, Function, Object, and recently in Symbol is added as the Building block of JavaScript. But the list is not ended yet. In the building blocks things, there is null and undefined also.

Two types of Number:
The latest version of ECMAScript released a new numeric type, which is “BigInt”. Before then, we just knew the “Number” type. Like, integer, float, double are the number type…


  1. indexOf(): The indexOf() method is used to get the index of the first occurrence of specified characters in a string. The search will start from the beginning of the string. Its default index is 0. If the value is not found, it returns -1. The indexOf() method is case sensitive. The following example uses the indexOf().
let str = "I'm learning web development.";
let index = str.indexOf("e");
console.log(index);
//output: "I'm l'e'arning web development. from the beginnig is 5."

2. lastIndexOf(): The lastIndexOf() method is used to get the index of the last occurrence of specified characters in a string. indexOf()…


1. What are the major features of React?

Answer: The major features of React are:

  • It uses VirtualDOM instead of RealDOM considering that RealDOM manipulations are expensive.
  • Supports server-side rendering.
  • Follows Unidirectional data flow or data binding.
  • Uses reusable/composable UI components to develop the view.

2. What are the advantages of React?

Answer :

  • Increases the application’s performance with Virtual DOM.
  • JSX makes code easy to read and write.
  • It renders both on the client and server-side (SSR).
  • Easy to integrate with frameworks (Angular, Backbone) since it is only a view library.
  • Easy to write unit and integration tests with tools such as Jest.

3 . What is the difference between Element and Component?

Answer: A React Element is what gets returned from components. It’s…


1 . What are the differences between == and === ?

Answer: The difference between ==(abstract equality) and ===(strict equality) is that the == compares by value after coercion and === compares by value and type without coercion.

Rules of implicit coercion :

  • If one operand is a string and another is a number, the string will be converted to a number.
  • if one operand is Boolean and the others are non-boolean, Boolean will be converted to a number.
  • While comparing a string or number with an object, the object will be converted to a primitive type.

2. Explain Event Bubbling?

Answer: When an event is triggered from an element, the event handler/event listener tied…


1 . Define Semantic elements in HTML .

Ans: Semantic HTML elements are those that clearly describe their meaning in a human- and machine-readable way. Elements such as <header>, <footer>, and <article> are all considered semantic because they accurately describe the purpose of the element and the type of content that is inside them.

2. Why meta tags are used in HTML?

Ans: Meta tags in HTML are used by the developer to tell the browser about the page description, author of the template, character set, keywords, and many more. …

Satodhru Nondon

Junior Web Developer

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