1What is Node.js? What is it used for?
2
3Q2. What is Event-driven programming?
4
5Q3. What is Event loop in Node.js work? And How does it work?
6
7Q4. What is REPL in Node.js?
8Q5. What is the purpose of module.exports in Node.js?
9
10Q6. What is the difference between Asynchronous and Non-blocking?
11
12Q7. What is Tracing in Node.js?
13
14Q8. How will you debug an application in Node.js?
15
16Q9. Difference between setImmediate() vs setTimeout()
17
18Q10. What is process.nextTick()
19vent loop continues.
20Q11. What is package.json? What is it used for?
21
22Q12. What is libuv?
23libuv is a multi-platform support library with a focus on asynchronous I/O. It was primarily developed for use by Node.js, but it’s also used by Luvit, Julia, pyuv, and others.
24When the node.js project began in 2009 as a JavaScript environment decoupled from the browser, it is using Google’s V8 and Marc Lehmann’s libev, node.js combined a model of I/O – evented – with a language that was well suited to the style of programming; due to the way it had been shaped by browsers. As node.js grew in popularity, it was important to make it work on Windows, but libev ran only on Unix. libuv was an abstraction around libev or IOCP depending on the platform, providing users an API based on libev. In the node-v0.9.0 version of libuv libev was removed.
25Some of the features of libuv are:
26Full-featured event loop backed by epoll, kqueue, IOCP, event ports.
27Asynchronous TCP and UDP sockets
28Asynchronous file and file system operations
29Child processes
30File system events
31Q13. What are some of the most popular modules of Node.js?
32There are many most popular, most starred or most downloaded modules in Node.js. Some of them are:
33express
34async
35browserify
36socket.io
37bower
38gulp
39grunt
40Q14. What is EventEmitter in Node.js?
41All objects that emit events are instances of the EventEmitter class. These objects expose an eventEmitter.on() function that allows one or more functions to be attached to named events emitted by the object.
42When the EventEmitter object emits an event, all of the functions attached to that specific event are called synchronously.
43

1
2<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">addNode</span>(<span class="hljs-params"></span>) </span>{ <span class="hljs-keyword">var</span> newP = <span class="hljs-built_in">document</span>.createElement(<span class="hljs-string">"p"</span>);
3										<span class="hljs-keyword">var</span> textNode = <span class="hljs-built_in">document</span>.createTextNode(<span class="hljs-string">" This is a new text node"</span>);
4										newP.appendChild(textNode); <span class="hljs-built_in">document</span>.getElementById(<span class="hljs-string">"firstP"</span>).appendChild(newP); }
5
6

1var emp = {
2name: "Daniel",
3age: 23
4};
5

1 var str = "Vivek Singh Bisht"; //using double quotes
2 var str2 = 'John Doe'; //using single quotes
3

1var readline = require('readline');
2
3var rl = readline.createInterface({
4  input: process.stdin,
5  output: process.stdout
6});
7
8rl.question("What do you think of node.js? ", function(answer) {
9  console.log("Thank you for your valuable feedback:", answer);
10
11  rl.close();
12});
13

1// What is the Output var Employee = {    company: 'xyz'}var emp1 = Object.create(Employee);delete emp1.companyconsole.log(emp1.company);// Output  'xyz'