Question 1

What is Express.js?

Accepted Answer

Express.js is an open-source, simple, and lightweight backend web application framework for Node.js. It is commonly used for building server-side web and RESTful APIs using JavaScript. Moreover, it also provides the convenience of setting up middleware, HTTP requests, and routing.

Question 2

Explain the difference between Node.js and Express.js.

Accepted Answer

Node.js is the runtime environment for JavaScript, and Express.js is a framework for Node.js. Using Node.js, developers can use JavaScript for server-side applications. Whereas Express.js frameworks provide plenty of tools through which developers can easily create web and API applications.

Question 3

Explain the control flow function.

Accepted Answer

Whenever the asynchronous function calls are made, a code snippet is executed; this code is called the control flow function. It also scrutinizes the order of these functions that are executed in Node.js.

Question 4

Can you tell me what Bcrypt is in Express.js?

Accepted Answer

Bcrypt is used to securely store the user's password. It works against attacks such as brute force and rainbow tables.

Question 5

What is a test pyramid?

Accepted Answer

It is a concept used in the software testing phase that consists of three levels, i.e., unit tests, integration tests, and end-to-end (E2E) tests. It suggests that more tests should be conducted at the base, and as we move forward, fewer tests should be conducted.

Question 6

Why do we use ESLint in Express.js?

Accepted Answer

EsLint detects the faulty patterns that are discovered in ECMAScript and JavaScript code. The main purpose of using this is to improve the quality of code and prevent bugs.

Question 7

What are the databases that Express.js integrates with?

Accepted Answer

Express.js integrates well with PostgreSQL, SQLite, MySQL, and MongoDB.

Question 8

Do we use the Response.cookie()’ function in Express.js?

Accepted Answer

Yes, we use this function to set cookies in the HTTP response. Cookies are commonly used to store information about the use.

Question 9

Why do we need to sanitize the input process in Express JS?

Accepted Answer

This is done to enhance security and get rid of attacks such as cross-site scripting (XSS) and SQL injection. It further checks whether the code contains any malicious code that can pose a security threat to the application. Therefore, it always cleans and validates user input.

Question 10

How do you handle errors in Express.js?

Accepted Answer

By simply using the built-in error and next() functions. Whenever an error occurs, we use the next() function to pass the next middleware or route handler.

Question 11

What do you mean by scaffolding in Express.js?

Accepted Answer

It is a way to generate the basic structure automatically. It is useful for maintaining consistency in large projects.

Question 12

Is Express.js a framework?

Accepted Answer

Yes, it is a framework for server-side web applications. It is well-known for its simplicity, flexibility, and scalability. Also, it provides convenience for setting up middleware and routing.

Question 13

Tell me the difference between Django and Express.js.

Accepted Answer

Express.js is a Node.js framework used to build single-page, multi-page, and hybrid web applications and APIs. Django is a Python web framework that runs under the MTV (Model Template View) architecture.

Question 14

What skills are crucial for Express.js developers?

Accepted Answer

SQLite and Node.js expertise are important for Express.js developers.

Question 15

Name a few third-party middlewares that are offered by Express JS.

Accepted Answer

Middlewares are provided by Express. js are Mongoose, Express-validator, Body-parser, Cors, and Sequelize.

Question 16

Tell me the difference between router-level middleware and built-in middleware.

Accepted Answer

Router-level middleware is used to bind the instance of Express. Router(). Whereas, by using the built-in middleware, developers can remove the dependency.

Question 17

Explain how the plain HTML is rendered.

Accepted Answer

We can use the res.sendFile() function with the particular file. There is no need for rendering with the function res.render() in HTML. When dealing with several assets from a directory, we can directly use the Express.static() middleware function.

Question 18

Mention the scenarios where cross-origin resources fail in Express JS.

Accepted Answer

If there is a discrepancy in the origin specified in the Access-Control-Allow-Origin header with the one you're requesting. 
 
 Sometimes browsers set limitations on HTTP methods. 
 
 If the cross-origin resources are from a different port. 
 
 When cross-origin resources are from a different subdomain. 
 
 The last scenario is when cross-origin resources are from different protocols.

Question 19

Write down the command to install Yeoman for scaffolding.

Accepted Answer

First, you have to write npm install -g yo in order to install Yeoman. 
 
 This command, npm install -g generator-express, creates the structure for the project and establishes the configuration. 
 
 After the successful installation, you can use Yeoman to create a new application by writing this command: yo appname.

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