How can you avoid callbacks?

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.

Question:- Does Node.js provide Debugger?

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.

Question:- What is a control flow function?

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

Question:- How "Control Flow" controls the functions 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

Question:- Is it possible to access DOM in Node?

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

Question:- What types of tasks can be done asynchronously using the event loop?

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

Question:- What is REPL in Node.js?

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.

Question:- Explain the tasks of terms used in Node REPL.

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.

Question:- Is it possible to evaluate simple expressions using Node REPL?

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

Question:- Does Node.js supports cryptography?

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.

Question:- What is npm? What is the main functionality of npm?

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.

Question:- What tools can be used to assure a consistent style in Node.js?

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

Question:- What is the difference between operational and programmer errors?

Answer:- Operational errors are not bugs, but create problems with the system like request timeout or hardware failure. On the other hand, programmer errors are actual bugs.

Question:- What is the difference between the global installation of dependencies and local installation of dependencies?

Answer:- • Global installation of dependencies is stored in /npm directory. While local installation of dependencies stores in the local mode. Here local mode refers to the package installation in node_modules directory lying in the folder where Node application is present. • Globally deployed packages cannot be imported using require() in Node application directly. On the other hand, locally deployed packages are accessible via require(). • To install a Node project globally -g flag is used. C:Nodejs_WorkSpace>npm install express ?g • To install a Node project locally, the syntax is: C:Nodejs_WorkSpace>npm install express