Answer:- All the APIs of Node.js library are asynchronous means non-blocking. A Node.js based server never waits for an API to return data. The Node.js server moves to the next API after calling it, and a notification mechanism of Events of Node.js responds to the server for the previous API call.

Answer:- To avoid callbacks, you can use any one of the following options: • You can use modularization. It breaks callbacks into independent functions. • You can use promises. • You can use yield with Generators and Promises.

Answer:- To avoid callbacks, you can use any one of the following options: • You can use modularization. It breaks callbacks into independent functions. • You can use promises. • You can use yield with Generators and Promises.

Answer:- Yes, Node.js provides a simple TCP based protocol and built-in debugging client. For debugging your JavaScript file, you can use debug argument followed by the js file name you want to debug.

Answer:- Control flow function is a generic piece of code that runs in between several asynchronous function calls.

Answer:- The control flow does the following job: • Control the order of execution • Collect data • Limit concurrency • Call the next step in a program

Answer:- No, it is not possible to access DOM in Node.

Answer:- • I/O operations • Heavy computation • Anything requiring blocking

Answer:- REPL stands for Read Eval Print Loop. It specifies a computer environment like a window console or Unix/Linux shell where you can enter a command, and the computer responds with an output. It is very useful in writing and debugging the codes. REPL environment incorporates Node.js.

Answer:- Following are the terms used in REPL with their defined tasks: • Read: It reads users input; parse the input into JavaScript data-structure and stores in memory. • Eval: It takes and evaluates the data structure. • Print: It is used to print the result. • Loop: It loops the above command until user press ctrl-c twice to terminate.

Answer:- Yes. You can evaluate simple expressions using Node REPL.

Answer:- Yes, Node.js Crypto module supports cryptography. It provides cryptographic functionality that includes a set of wrappers for open SSLs hash HMAC, cipher, decipher, sign and verify functions.

Answer:- npm stands for Node Package Manager. Following are the two main functionalities of npm: • Online repositories for node.js packages/modules which are searchable on search.nodejs.org • Command line utility to install packages, do version management and dependency management of Node.js packages.

Answer:- Following is a list of tools that can be used in developing code in teams, to enforce a given style guide and to catch common errors using static analysis. • JSLint • JSHint • ESLint • JSCS