devarajchidambaram’s gists

devarajchidambaram / index.js

Created October 8, 2018 14:09

Pure vs Impure function

	/**
	Characteristics of Pure Function:

	The return value of the pure functions solely depends on its arguments Hence, if you call the pure functions with the same set of arguments, you will always get the same return values.

	They do not have any side effects like network or database calls

	They do not modify the arguments which are passed to them
	Characterisitcs of Impure functions

devarajchidambaram / closure.js

Created October 4, 2018 12:02

closure

	const arr = [10, 12, 15, 21];

	for (var i = 0; i < arr.length; i++) {
	(function(i){
	setTimeout(function() {
	console.log('The index of this number is: ' + i);
	}, 3000);
	})(i)

	}

devarajchidambaram / eventdelegation.html

Created October 4, 2018 11:58

Event delegation in js

	<!---
	Event delegation in JS
	Ref
	https://medium.freecodecamp.org/3-questions-to-watch-out-for-in-a-javascript-interview-725012834ccb
	-->

	<html>

	<body>
	<ul id="todo-app">

devarajchidambaram / index.js

Created October 4, 2018 05:06

Parseint vs Number in js

devarajchidambaram / index.js

Created September 28, 2018 11:10

DNS lookup vs resolve

	/**These functions are implemented quite differently than dns.lookup(). They do not use getaddrinfo(3) and they always perform a DNS
	query on the network. This network communication is always done asynchronously, and does not use libuv's threadpool.

	Always use DNS.resolve it network operations
	Dont use use DNS.lookup its uses the threadpool (Thread pool is limited)**/

devarajchidambaram / text

Created September 7, 2018 07:49

List of Automation testing libraries for nodejs

	Provide a testing structure (Mocha, Jasmine, Jest, Cucumber)
	Provide assertions functions (Chai, Jasmine, Jest, Unexpected)
	Generate, display, and watch test results (Mocha, Jasmine, Jest, Karma)
	Generate and compare snapshots of component and data structures to make sure changes from previous runs are intended (Jest, Ava)
	Provide mocks, spies, and stubs (Sinon, Jasmine, enzyme, Jest, testdouble)
	Generate code coverage reports (Istanbul, Jest, Blanket)
	Provide a browser or browser-like environment with a control on their scenarios execution (Protractor, Nightwatch, Phantom, Casper)

devarajchidambaram / stubfs.js

Created September 7, 2018 07:28

How to stub fs.readFile functions

	const fs = require('fs')

	function readFile (filename) {
	if (fs.existsSync(filename)) {
	return fs.readFileSync(filename, 'utf8')
	}
	throw new Error('Cannot find file ' + filename)
	}

	describe('mocking individual fs sync methods', () => {

devarajchidambaram / Timeout

Created September 6, 2018 07:19

Timeout express bound

	var http = require('http');
	var srvr = http.createServer(function (req, res) {
	setTimeout(function(){
	res.write('Hello World!');
	res.end();
	}, 5000)
	});


	srvr.listen(8080);

devarajchidambaram / passport.js

Created August 30, 2018 07:18

Passport js sample

	/* EXPRESS SETUP */

	const express = require('express');
	const app = express();

	const bodyParser = require('body-parser');
	app.use(bodyParser.urlencoded({
	extended: true
	}));

devarajchidambaram / express_session.js

Created August 30, 2018 04:38

Express session in nodejs

	var express = require('express');
	var cookieParser = require('cookie-parser');
	var session = require('express-session');

	var app = express();

	app.use(cookieParser());
	//For every request the session id is assigned if there is no session id
	//We can attach fields in req.session.key = value pair
	app.use(session({

devaraj devarajchidambaram