Web Technology Experts Notes

Friday 24 July 2020

Scrum Tutorial - part 2

Question: What is Scrum Events?
There are prescribed events that are used in Scrum to create regularity and these are time-boxed events.
Following are 4 Events.

Sprint planning
Daily scrum
Sprint review
Sprint retrospective

Question: What is Product Backlog?
The Product Backlog is an ordered list of application/software/etc that is known to be needed in the product.
It is the single source of requirements for any changes to be made to the product.
The Product Owner is responsible for the Product Backlog, including its content, availability, and ordering.

Question: What is Sprint Backlog?
The Sprint Backlog is the set of Product Backlog items selected for the Sprint, plus a plan for delivering the product Increment and realizing the Sprint Goal.
The Sprint Backlog is a forecast by the Development Team about what functionality will be in the next Increment

Question: What is Increment?
The Increment is the sum of all the Product Backlog items completed during a Sprint and the value of the increments of all previous Sprints.

Question: What is Definition of DONE?
When a Product Backlog item or an Increment is described as “Done”, everyone must understand what "Done" means.
Before a Product Backlog Item is considered "done" or "complete", it must respect the following criteria (Defination may be similar to below):
--Unit Tests are written and passing
--Acceptance Tests are written and passing
--Accessibility testing using https://wave.webaim.org/
--Continuous Integration (CI) pipeline passing

Question: What is Burn-down Chart?
A chart which shows the amount of work which is thought to remain in a backlog. .

Question: What is Burn-up Chart?
A chart which shows the amount of work which has been completed..

Question: What is Coherent/Coherence?
The quality of the relationship between certain Product Backlog items which may make them worthy of consideration as a whole.

Question: What is Emergence?
The process of the coming into existence or prominence of new facts or new knowledge of a fact, or knowledge of a fact becoming visible unexpectedly.

Question: What is Empiricism?
It has three pillars: transparency, inspection and adaptation.

Question: What is Sprint Retrospective?
Scrum Event that is set to a time-box of 3 hours, or less, to end a Sprint.

Question: What is Technical Debt?
The typically unpredictable overhead of maintaining the product.

Question: What is Artifacts?
An object made by a human being, typically one of cultural or historical interest.

Question: What is Cancelling a Sprint?
A Sprint can be cancelled before the Sprint time-box is over. Only the Product Owner has the authority to cancel the Sprint, although he or she may do so under influence from the stakeholders, the Development Team, or the Scrum Master.

Question: Describe the Scrum Events in Details?

Sprint planning: A time-boxed event occurs at the beginning of a sprint where the team determines the product backlog items they will work.
Daily scrum: A is a 15-minute time-boxed event for the Development Team to synchronize activities and create a plan for the next 24 hours.
Sprint review: A time-boxed event holds at the end of the Sprint to inspect the Increment and adapt the Product Backlog if needed. In this the Scrum Team and stakeholders collaborate about what was done in the Sprint.
Sprint retrospective: Event for providing an opportunity for the Scrum Team to inspect itself and create a plan for improvements to be enacted during the next Sprint.

Thursday 23 July 2020

Python Interview Questions and Answers for Freshers

Question: What is current Stable version of Python?

Version: 3.5.1 Dated: 7 December 2015

Question: What is Filename extension of Python?
py, .pyc, .pyd, .pyo, pyw, .pyz

Question: What is offical website of Python?
www.python.org

Question: What is the difference between deep copy and shallow copy?

Shallow copy is used when a new instance type gets created and it keeps the values that are copied.
Deep copy is used to store the values that are already copied.
Shallow copy is used to copy the reference pointers just like it copies the values.
Shallow copy allows faster execution of the program whereas deep copy makes slow.

Question: How to use ternary operators?

[on_true] if [expression] else [on_false]
x, y = 25, 50
big = x if x < y else y

Question: What are different data-type in Python?

Numbers
Strings
Strings
List
Dictionaries
Sets

Question: What is module in python?
Module is set of related functionalities. Each python program file is a module, which imports other modules to use names they define using object.attribute notation.

Question: What is lambda in python?
lamda is a single expression anonymous function often used as inline function.

Question: How to validate Email Address in python?

re.search(r"[0-9a-zA-Z.]+@[a-zA-Z]+\.(com|co\.in)$","myemail@domain.com")

Question: What is pass in Python?
pass is no-operation Python statement and used to indicate nothing to be done.

Question: What is iterators?
iterators is used iterate over a group of elements, containers, like list

Question: What is slicing in Python?
Slicing is a mechanism to select a range of items from Sequence types like strings, list, tuple, etc.

Question: What is docstring in Python?
Python documentation string is a way of documenting Python modules, functions, classes. PEP 257 standardize the high-level structure of docstrings.

Question: Name few modules that are included in python by default?

datetime
re (regular expressions)
string
itertools
ctypes
email
xml
logging
os
subprocess

Question: What is list comprehension?
Creating a list by doing some operation over data that can be accessed using an iterator.

>>>[ord(i) for i in string.ascii_uppercase]
     [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90]
 >>>

Question: What is map?
MAP executes the function given as the first argument on all the elements of the iterable given as the second argument.

Question: What is the difference between a tuple and a list?
A tuple is immutable i.e. can not be changed. It can be operated on only.
List is mutable. Changes can be done internally to it.

Question: How to Remove white spaces from string?

filter(lambda x: x != ' ', s)

Question: What are metaclasses in Python?
A metaclass is the class of a class.
A class defines how an instance of the class (i.e. object) behaves while a metaclass defines how a class behaves. A class is an instance of a metaclass.

Question: How do I check whether a file exists without exceptions?

os.path.isfile("/etc/password.txt");//true

Question: How to call an external command?

import subprocess
subprocess.run(["ls", "-l"])

Scrum Tutorial - part 1

Question: What is Scrum?
Scrum is an agile framework which is used for developing, delivering the software products.
Now its also used in other fields like research, sales and marketing.

Question: Who is Scrum team?

Product owner:
The Product Owner is responsible for maximising the value of the product resulting from work of the Development Team.
Developers:
The Development Team consists of professionals who do the work.
Scrum Master:
The Scrum Master is responsible for promoting and supporting Scrum as defined in the Scrum Guide.

Question: What are uses of Scrum?

Research and identify viable markets, technologies, and product capabilities
Develop products and enhancements
Develop and sustain Cloud (online, secure, on-demand) and other operational environments for product
Maintain products

Question: What are 3 pillars of Scrum?

Transparency
What task have done and what are pending and what team are doing will be visible to the Scrum team members and stockholder of product.
Inspection
Scrum users must frequently inspect Scrum artifacts and progress.
Adaptation
If an inspector determines that one or more aspects, then that can be taken.

Question: What are events of scrum?

Sprint Planning
Daily Scrum
Sprint Review
Sprint Retrospective

Question: What are Scrum Master Service to the Product Owner?

Finding techniques for effective Product Backlog management
Helping the Scrum Team understand the need for clear and concise items
Ensuring the Product Owner knows how to arrange the Product Item to maximize value
Facilitating Scrum events as requested or needed.
Ensuring that goals, scope, and product domain are understood by everyone on the Scrum Team

Question: What are Scrum Master Service to the Product Owner?

Removing impediments to the Development Team’s progress
Coaching the Development Team in self-organization and cross-functionality
Facilitating Scrum events as requested or needed
Coaching the Development Team
Helping the Development Team to create high-value products

Question: What are Scrum Master Service to the Organisation?

Causing change that increases the productivity of the Scrum Team
Leading and coaching the organisation in its Scrum adoption
Planning Scrum implementations within the organisation
Helping employees and stakeholders

Wednesday 22 July 2020

How to determine a user's IP address in node

Question: How to determine a user's IP address in node?
We can use request.connection.remoteAddress to detect the IP Address in node but sometimes server is running behind the load balancer, In this case we need to check for x-forwarded-for

Example

exports.check_node = function(req, res) {
    var ip = req.headers['x-forwarded-for'] || 
     req.connection.remoteAddress || 
     req.socket.remoteAddress ||
     (req.connection.socket ? req.connection.socket.remoteAddress : null);
    
    res.json({ip:ip});
};

Question: How can I use wait In Node.js?
You can use setTimeout function similar to javascript

Example

function function1() {    
    console.log('Welcome to My Console,');
}

function function2() {    
    console.log('Console2');
}

setTimeout(function2, 3000); //call second
function1(); //Call first

Question: Command to remove all npm modules in windows?

Remove module local
Go to directory with name of node_modules under current project. DELETE all the folder.
C:\Users\DELL\AppData\Roaming\npm\node_modules
Delete all the files

Question: Node.js check if path is file or directory?
For this, you need to install the fs module.

var fs = require('fs');
stat = await fs.lstat(PATH_HERE)
stats.isFile()
stats.isDirectory()
stats.isBlockDevice()
stats.isCharacterDevice()
stats.isSocket()

Question: What is use of app.use in express?
app.use is a method to configure the middleware used by Express.

Question: Difference between process.stdout.write and console.log?
console.log() calls process.stdout.write with formatted output.
console.log() explains in library

console.log = function (d) {
  process.stdout.write(d + '\n');
};

Question: How to Detect if file called through require or directly by command line?

if (require.main === module) {
    console.log('called directly');
} else {
    console.log('required as a module');
}

Question: What is the use of next() in express?
It passes control to the next matching route.

For Example:

app.get('/user/:id?', function(req, res, next){
    var id = req.params.id;
    if (id) {
        // do something
    } else {
        next(); 
    }
});

How to Call async/await functions in parallel

Question: How to Call async/await functions in parallel?
We can use await on Promise.all()

Syntax

let [someResult, anotherResult, anotherResult3] = await Promise.all([someCall(), anotherCall(), another3Call()]);

Example

const promise1 = Promise.resolve(3);
const promise2 = 42;
const promise3 = new Promise((resolve, reject) => {
  setTimeout(resolve, 100, 'foo');
});
Promise.all([promise1, promise2, promise3]).then((values) => {
  console.log(values);
});

Question: How to read data from Image url and write in file synchronous?
First, We must need to install https and fs module in node.
https - Its for execute the https request.
fs - for save the file in local.

Example

const https = require('https');
const fs = require('fs');

const file = fs.createWriteStream("file.jpg");//Create  a file
const request = https.get("https://img.youtube.com/vi/0yX92mE6h2M/mqdefault.jpg", function(response) {
  response.pipe(file);//Add the image-content in file
});

Question: What is difference between app.listen and server.listen?
Both are used to start the server, for listening the request.

We need server.listen for create the request on https server.

var https = require('https');
var server = https.createServer(app).listen(config.port, function() {
    console.log('Https App started');
});

app.listen will create http server.

var express = require('express');
var app = express();
app.listen(1234);

Question: How to return the json response?
You can use res.json() to return the response in APIs
Example

exports.get_data = function(req, res) {  
    res.json({name: "web technology experts",description:"this is description"});
};

Question: How to auto-reload files in Node.js in Local server?
While doing the development, you do not want to re-start the node server each time, when you made changes.
For this you can use nodemon module.
Install the nodemon module

npm install nodemon -g

start the node with nodemon instead of node

nodemon app.js

Question: How to create https request?
To Create the https server,
---first you need to install the modules like https, express and socket.io etc
---You need private/public keys for ssl

var https = require('https');
var privateKey  = fs.readFileSync('public/server.key', 'utf8');
var certificate = fs.readFileSync('public/file.crt', 'utf8');
var caCertificate = fs.readFileSync('public/chain.crt', 'utf8');
var credentials = {key: privateKey, cert: certificate, ca: caCertificate};
var httpsServer = https.createServer(credentials, app);  
var io = require('socket.io')(httpsServer);  
httpsServer.listen(443,function() {
    console.log('https listening on 443');
});

Monday 20 July 2020

Call socket event from router page in Node

Question: How to send socket notification from Node API/Router?

In App file (like index.js OR app.js)

//Express setup
var express = require('express');
var app = express();

//socketsetup setup
var io = require('socket.io')(https);    
app.set('io', io); //IMP this will let available io in router file

In Router or Controller file

exports.sendnotify = function(req, res) {
    var io = req.app.get('io');
    io.sockets["in"]('room_446').emit('session_end_notify', {vid:100,event_type:'live'});   //Send the Notification
    res.send('node is working fine');
};

Question: How decrypt a text which is encoded with base64?

let buff = Buffer.from('ENCRYPTED_TXT', 'base64');
print buff.toString('ascii');

Thursday 2 July 2020

Node JS Interview Questions and Answers

Question: How to write in files synchronous in Node.js?

const fs = require('fs');
fs.writeFileSync('/fold/test.txt', 'Write in file');

Question: What is the difference between --save and --save-dev?
--save-dev is used to save the package for development purpose. Example: unit tests, minification
--save is used to save the package required for the application to run.

Question: is node single threaded or multithreaded?
It is a single threaded language which in background uses multiple threads to execute asynchronous code. Also its is non-blocking which means that all functions ( callbacks ) are delegated to the event loop and they are ( or can be ) executed by different threads.

Question: How to print console without a trailing newline?

    process.stdout.write("hello: ");

Question: How to create a directory if it doesn't exist using Node.js?

var fs = require('fs');
var dir = './tmp';
if (!fs.existsSync(dir)){
    fs.mkdirSync(dir);
}

Question: How can we execute binary/exe files in Node ?

const { exec } = require('child_process');
exec('wc -l', (err, stdout, stderr) => {
  if (err) {
    // node couldn't execute the command
    return;
  }
});

Question: Is there a way to get version from package.json?

var pjson = require('./package.json');
console.log(pjson.version);

Question: How can I update npm on Windows?
Simple way
Download and run the latest MSI from nodejs.org. The MSI will update your installed node and npm.

Question: How can node in background?

nohup node server.js &

Question: What is the difference between __dirname and ./ in node.js?
__dirname is always the directory in which the currently executing script exist.
. gives you the directory from which you ran the node command in your terminal window

Question: How to get the full url in Express?

var url = require('url');
function fullUrl(req) {
  return url.format({
    protocol: req.protocol,
    host: req.get('host'),
    pathname: req.originalUrl
  });
}

Wednesday 1 July 2020

Node JS Interview Questions and Answers for 3 Years experience

Question: What is the difference between tilde(~) and caret(^) in package.json?
~ update you to all future patch versions, without incrementing the minor version. ~2.2.3 will use releases from 2.2.3 to 2.3.0.
^ update you to all future minor/patch versions, without incrementing the major version. ^2.3.3 will use releases from 2.3.3 to 3.0.0.

Question: How do I pass command line arguments to a Node.js program?
In Node - How to pass arguent

node process-2.js one two=three four

In Node - How to get argument value

process.argv

Question: How do I update each dependency in package.json to the latest version?

npm i -g npm-check-updates
ncu -u
npm install

Question: How can I update NodeJS and NPM to the next versions?

npm install -g npm

Question: How to write in files synchronous in Node.js?

const fs = require('fs');
fs.writeFileSync('/fold/test.txt', 'Write in file');

Question: How to read environment variables?

var mode   = process.env.NODE_ENV;
var apiKey = process.env.apiKey;

Question: How to parse JSON using Node.js?

//Parse JSON Data
var bodyParser = require('body-parser')
app.use(bodyParser.json());       // to support JSON-encoded bodies
app.use(bodyParser.urlencoded({// to support URL-encoded bodies
    extended: true
}));

Question: How an HTTP POST request made?

var request = require('request');
request.post(
    'https://www.example.com',
    { json: { key: 'value' } },
    function (error, response, body) {
        if (!error && response.statusCode == 200) {
            console.log(body);
        }
    }
);

Question: How can I get the full object in Node.js's console.log(), rather than Object?

const util = require('util');
console.log(util.inspect(myObject, {showHidden: false, depth: null}));

OR
console.log(JSON.stringify(myObject, null, 4));

Question: How to encode a text using base64?

Buffer.from("Hello World").toString('base64'); //SGVsbG8gV29ybGQ=

Question: How to decoded a text which is encoded with base64?

Buffer.from("SGVsbG8gV29ybGQ=", 'base64').toString('ascii'); //Hello World

Thursday 18 June 2020

Get Mysql Row size too large error when change engine from MyISAM to Innodb

ALTER TABLE table_name ENGINE=InnoDB

When i try to change the engine From MyISAM to InnoDB, getting following error.

row size too large (> 8126). changing some columns to text or blob or using row_format=dynamic or row_format=compressed may help.

Solutions:

Add the following to the my.cnf file under [mysqld] section.

        innodb_file_per_table=1;
        innodb_file_format = Barracuda;
        innodb_log_file_size = 256M

ALTER TABLE table_name ENGINE=InnoDB ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8;

Sunday 7 June 2020

MySQL database Administrator interview question and Answer for 6 year experienced

Question: How to reset AUTO_INCREMENT in MySQL?>

ALTER TABLE tablename AUTO_INCREMENT = 1

Question: How to concatenate multiple rows into one field?>

SELECT GROUP_CONCAT(id SEPARATOR ', ')   FROM users   WHERE city = 'india'  GROUP BY city;

(It will concatinate all the users)

Question: Which MySQL data type to use for storing boolean values?>

BIT

Question: What are best character-set for multi-language data?>

utf8mb4

Question: What is the difference between utf8mb4_unicode_ci and utf8mb4_general_ci?
utf8mb4_unicode_ci is based on the official Unicode rules for universal sorting and comparison, which sorts accurately in a wide range of languages.

utf8mb4_general_ciis a simplified set of sorting rules which aims to do as well as it can while taking many short-cuts designed to improve speed. It does not follow the Unicode rules and will result in undesirable sorting or comparison in some situations

Question: How do you set a default value for a MySQL Datetime column?>
Add the default CURRENT_TIMESTAMP
For example:

CREATE TABLE foo (
    `modification_time` DATETIME ON UPDATE CURRENT_TIMESTAMP
)

Question: What is the difference between physical and logical backup?>
physical backup is to copy for backing up all the physical files that belongs to database.(like data files,control files,log files, executables etc), we need to stop the mysql service temporary.>
In logical backup, you don't take the copies of any physical things,you only extract the data from the data files into dump files.(ex : using export )

Question: What are World's most popular Databases?>

Oracle
MySQL
Microsoft SQL Server
PostgreSQL
MongoDB

Question: Explain ACID?
Atomicity. All completed OR Nothing.
Consistency. Database protected from actions that may corrupt data.
Isolation. multiple actions occuring in parallel will not impact each other.
Durability. All commited statements data are safe.

Question: What does FLUSH TABLES WITH READ LOCK do?
1 set the global read lock - after this step, insert/update/delete/replace/alter statements cannot run.
2 close open tables - this step will block until all statements started previously have stopped.
3 set a flag to block commits.

FLUSH TABLES

Thursday 4 June 2020

MySQL database Administrator interview question and Answer

MySQL database Administrator interview questions and Answer

Question: How to start MySQL Service?
Start MySQL Server using service

sudo service mysql start

Start MySQL Server using using init.d

sudo /etc/init.d/mysql start

Start MySQL Server using systemd

Start MySQL Server using systemd

Question: List the MySQL Users

select user from mysql.user;

Question: List all databases

show databases

Question: Grant insert,UPDATE,delete privileges on the mydb (DB) to dbuser (User)

GRANT INSERT, UPDATE, DELETE ON mydb.* TO bob@localhost;

Question: Grant all privileges on the mydb (DB) to dbuser(User)

grant all privileges on mydb.* to dbuser@localhost;

Question: Show all the privileges to dbuser(User)

SHOW GRANTS FOR dbuser;

Question: Revoke insert,UPDATE,delete privileges on the mydb (DB) from dbuser (User)

REVOKE INSERT, UPDATE ON mydb.* FROM dbuser@localhost;

Question: List all the Proesslist in MySQL

SHOW Full PROCESSLIST

Question: What are different MySQL storage engines

MyISAM: Before MySQL version 5.5, MyISAM is the default storage engine. MyISAM extends the former ISAM storage engine. MyISAM tables are optimized for compression and speed. MyISAM tables can be compressed into read-only tables to save spaces. The MyISAM tables are not transaction-safe. MySQL also checks and repairs InnoDB tables.
InnoDB: InnoDB tables fully support ACID-compliant and transactions. InnoDB table supports foreign keys, commit, rollback, roll-forward operations. MySQL also checks and repairs InnoDB tables.
MERGE: A MERGE table is a virtual table that combines multiple MyISAM tables that have a similar structure to one table. MERGE table does not have its own indexes;
MEMORY: The memory tables are stored in memory and use hash indexes so that they are faster than MyISAM tables The lifetime of the data of the memory tables depends on the uptime of the database server.

Monday 1 June 2020

MySQL Stored procedure interview Questions and Answer

Question: What is stored procedure?
A stored procedure is Structured Query Language (SQL) statements which has a name, a parameter list, and SQL statement(s) stored in MySQL Server.

Question: Give example of stored procedure?

DELIMITER $$
CREATE PROCEDURE getUsersAscending()
BEGIN
	SELECT 
		first_name, 
		last_name, 
		email
	FROM
		users
	ORDER BY first_name;    
END$$
DELIMITER ;

Question: Give example of stored procedure with parameter details?

DELIMITER $$
CREATE   PROCEDURE `getUsersDetails`(IdSearch INT)    
    BEGIN
	SELECT 
		first_name, 
		last_name, 
		email
	FROM
		users
	WHERE id=IdSearch;      

    END$$
DELIMITER ;

Question: To show all stored procedures:

SHOW PROCEDURE STATUS;

Question: How to show stored procedures in a specific database

SHOW PROCEDURE STATUS WHERE Db = 'db_name';

Question: MySQL stored procedures advantages?

Reduce network traffic
Make database more secure

Question: MySQL stored procedures dis-advantages?

Resource usages: If you use many stored procedures, the memory usage of every connection will increase substantially.
Troubleshooting:MySQL does not provide any facilities to debug stored procedures like other enterprise database products such as Oracle and SQL Server
Maintenances Developing and maintaining stored procedures often requires a specialized skill set that not all application developers possess.

Question: How to call stored procedure with OR without arguments?
Call without argument

call getUsersAscending();

Call With argument

call getUsersDetails(10);

Question: How to delete the procedure?

DROP PROCEDURE IF EXISTS getUsersAscending;

Question: What if i am trying to delete the stored procedure for non-exist.?
It will give warning only, if you have used "IF EXISTS"
It will give Error, if you have used not used "IF EXISTS"

Question: How to Alter a stored procedure in mysql?
1: Delete the Stored procedure.

2: Re-Create the Stored procedure.

Sunday 31 May 2020

AWS Elastic Beanstalk Interview Questions and Answers

Question: What is Elastic Beanstalk in AWS?
AWS Elastic Beanstalk is End-to-end web application management.

Question: Can we use Elastic beanstalk to deploy the web application which is made in Node OR PHP?
Yes, AWS Elastic Beanstalk is service for deploying and scaling web applications and services developed with Java, .NET, PHP, Node.js, Python, Ruby, Go, and Docker on familiar servers such as Apache, Nginx, Passenger, and IIS.

Question: How does works Elastic Beanstalk?
You simply upload your code and Elastic Beanstalk automatically handles the deployment, from capacity provisioning, load balancing, and automatic scaling to web application health monitoring, with ongoing fully managed patch and security updates.

What are Benefits and features of Elastic Beanstalk?

Easy to get started
Elastic Beanstalk is the simplest way to deploy and run your web application on AWS.
Complete resource control
You have the freedom to select the AWS resources, such as Amazon EC2 instance types, that are optimal for your web application.
Fully managed: update your web application with the latest platform security and patch updates.
Automatic application health monitoring
Elastic Beanstalk automatically collects more than 40 key metrics and attributes to determine the health of your web application

Question: What Language Supported by Elastic Beanstalk

Go
Java SE
Java with Tomcat
NET on Windows Server with IIS
Node.js
PHP
Python
Ruby
Packer Builder

Question: How is AWS CloudFormation different from AWS Elastic Beanstalk?
AWS CloudFormation helps you provision and describe all of the infrastructure resources that are present in your cloud environment. On the other hand, AWS Elastic Beanstalk provides an environment that makes it easy to deploy and run applications in the cloud.
AWS CloudFormation supports the infrastructure needs of various types of applications, like legacy applications and existing enterprise applications. On the other hand, AWS Elastic Beanstalk is combined with the developer tools to help you manage the lifecycle of your applications.

Question: Who should use AWS Elastic Beanstalk?
Those who want to deploy and manage their applications within minutes in the AWS Cloud. You don’t need experience with cloud computing to get started. AWS Elastic Beanstalk supports Java, .NET, PHP, Node.js, Python, Ruby, Go, and Docker web applications.

Saturday 30 May 2020

PHP 7 Scalar type declarations and return type declarations

What is a Scalar type declarations?
Allowing/Not-Allowing datatype declaration in functions is known as Scalar type declarations.

Question: What are different types of Scalar type declarations?
1) Coercive Mode (default)
2) Strict Mode

What are different type of data-type can be used in Scalar type declarations?

int
float
bool
string
interfaces
array
callable

Question: Give the examples of Scalar type declarations with Coercive Mode (default)
Example 1

$a=1; // integer
$b=2; //integer
function FunctionName1(int $a, int $b){
return $a + $b;
}
echo FunctionName1($a, $b); //3

Example 2

   function sum(int ...$ints) {
      return array_sum($ints);
   }

   print(sum(3, '2', 5.1)); //10

Example 3

function FunctionName3(int $a, int $b){
return $a * $b;
}

echo FunctionName3('hello', 10); //PHP Fatal error: Uncaught TypeError: Argument 1 passed to FunctionName() must be of the type integer, string given.

Example 4

$a='1One'; 
$b=2; //integer
function FunctionName3(int $a, int $b){
return $a + $b;
}
echo FunctionName3($a, $b);//RESULT: PHP Notice: A non well formed numeric value encountered on line 5

Question: Give the examples of Scalar type declarations with STRICT MODE?
Example 1

declare(strict_types=1); 

$a=1; // integer
$b=2; //integer
function phpFunction (int $a, int $b){
return $a + $b;
}

echo phpFunction1($a, $b);//3

Example 2

declare(strict_types=1); 

$a='1'; // String
$b=2; //integer
function phpFunction1 (int $a, int $b){
return $a + $b;
}

echo phpFunction1($a, $b);//Fatal error: Uncaught TypeError: Argument 1 passed to phpFunction1() must be of the type int, string given

Question: Give the examples of Return type declarations with STRICT MODE?
Example 1

$a='10'; //  string
$b=2; // integer
function phpFunctionReturn ($a, $b) : int  {
return $a * $b;
}
echo phpFunctionReturn ($a, $b);

Example 2

declare(strict_types=1); 
$a='10'; //  string
$b=2; // integer
function phpFunctionReturn ($a, $b) : string  {
return $a * $b;
}
echo phpFunctionReturn ($a, $b);//PHP Fatal error:  Uncaught TypeError: Return value of phpFunctionReturn() must be of the type string, integer returned in /home/cg/root/7035270/main.php:6

Friday 29 May 2020

CSS3 interview questions and answers for experienced

Question: How to write conditional statement in CSS?

<!--[if IE 7]>
<style type="text/css">
div.abc {                 
    background-color:red;
}
</style>
<![endif]-->

Question: How to write styles for all html elements of the same type?
Use tag name to write the CSS.
See Example

h1{font-size:18px;}
h2{font-size:17px;}
h3{font-size:16px;}
h4{font-size:15px;}

Question: What are different vaules of position attributes?
absolute
fixed
inherit
relative
static

Question: How to display a link without underline using CSS?

 a{
    text-decoration:none;
}

Question: How to display a link without underline when mouseover on the link using CSS?

 a:hover{
    text-decoration:none;
}

Question: How to page break after an html element in CSS?

<div style="page-break-after: always;">
Web Technology Experts Notes</div>

Question: What is the default value of "position" attribute in css?
static

Question: How we can specify more than one css class for any HTML element?

<div class="class1 class2">
Web technology experts Notes</div>

Question: Is CSS case sensitive?
No

Question: What is ID selector?
ID selector is an individually identified selector to which a specific style is declared.

Question: How to set wait cursor?

div.click{
    cursor:wait;
}

Question: What is Tweening ?
It process of generating intermediate frames between two images to give the appearance that the first image evolves smoothly into the second image.

Question: What are Child Selectors?
A child selector is used when you want to match an element that is the child of another specific element.

div.abc > ul {font-weight: bold;}

Question: What are different ways to apply styles to a Web page
Inline
Embedded
Linked
Imported

Question: What is contextual selector
Contextual selector addresses specific occurrence of an element.

Question: How to disable text selection highlighting with CSS?

.noselect {
  -webkit-touch-callout: none; /* iOS Safari */
    -webkit-user-select: none; /* Safari */
     -khtml-user-select: none; /* Konqueror HTML */
       -moz-user-select: none; /* Old versions of Firefox */
        -ms-user-select: none; /* Internet Explorer/Edge */
            user-select: none; /* Non-prefixed version, currently
                                  supported by Chrome, Edge, Opera and Firefox */
}

Add the .noselect to the html tag

Saturday 18 April 2020

How to check if a number is prime?

Question: What is Prime Number
A prime number is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers.

Question: Give the example of Prime Number
2, 3, 5, 7, 11, 13, 17, 19, 23 and 29.

Question: Write an function that check the prime number OR Not?

function checkPrime($number){
    if($number < 0 ){
        return false;
    }
    $return=true;
    for($i=2; $i < $number; $i++){
        if($number % $i ==0){
            $return=false;
            break;
        }
    }
   return $return;
}

Question: How to check a number is prime Or Not?

echo checkPrime(2)?'Prime':'Not Prime'; //Prime
echo checkPrime(4)?'Prime':'Not Prime'; //Not Prime
echo checkPrime(6)?'Prime':'Not Prime'; //Not prime
echo checkPrime(7)?'Prime':'Not Prime';  //Prime

Question: What are the prime numbers between 1 to 100?

for( $i = 2; $i < 100; $i++ ){
    if( checkPrime( $i ) ){
        echo $i;
        echo ',';
    }
}

Wednesday 8 April 2020

Difference between mysql.createConnection and mysql.createPool in Node.js?

mysql.createConnection

When you create a connection with mysql.createConnection, you only have one connection and it lasts until you close it OR connection closed by MySQL.

A single connection is blocking. While executing one query, it cannot execute others. hence, your application will not perform good.
Example:

var mysql = require('mysql');
var connection = mysql.createConnection({
  host     : 'localhost',
  user     : 'root',
  password : '',
  database : 'mydb',
});

mysql.createPool

mysql.createPool is a place where connections get stored.
When you request a connection from a pool,you will receive a connection that is not currently being used, or a new connection.
If you're already at the connection limit, it will wait until a connection is available before it continues.

A pool while one connection is busy running a query, others can be used to execute subsequent queries. Hence, your application will perform good.
Example:

var mysql = require('mysql');
var pool  = mysql.createPool({
  connectionLimit : 10,
  host     : 'localhost',
  user     : 'root',
  password : '',
  database : 'mydb',
});

Tuesday 7 April 2020

How to check active connections in MySQL?

Question: How to check active connections in mysql?

show status where `variable_name` = 'Threads_connected';

Question: How to check the limit of MySQL active connections?

SHOW VARIABLES LIKE "max_connections";

Question: Display the list of active MySQL Process list?

show processlist;

Question: How to check the max no of connections used?

SHOW STATUS WHERE `variable_name` = 'Max_used_connections';

Question: MySQL set the max no of connections used (Temporarily/Quick)?

SET GLOBAL max_connections = 512;

Question: MySQL set the max no of connections used (Temporarily/Quick)?
Open my.cnf or my.ini in MySQL

max_connections = 512

service mysqld restart

Question: MySQL check number of connections throughout history?

show status like 'Connections%';

Sunday 5 April 2020

Laravel interview questions for 4 year experienced

Question: What is Server Requirements for Laravel 5.6?

PHP >= 7.1.3
PDO PHP Extension
Ctype PHP Extension
OpenSSL PHP Extension
XML PHP Extension
JSON PHP Extension
Mbstring PHP Extension
Tokenizer PHP Extension

Question: What is Laravel Dusk?
It is expressive, easy-to-use browser automation and testing API.

Question: What is Laravel Echo?
Event broadcasting, evolved. Bring the power of WebSockets to your application without the complexity.

Question: How to Install Laravel via Composer?

composer create-project --prefer-dist laravel/laravel myproject

Question: How to Install any Specific version of Laravel via Composer

composer create-project --prefer-dist laravel/laravel blog "5.4.*" //Install Laravel 5.4 using Composer

Question: What is Lumen?

Lumen is a micro-framework provided by Laravel.
It is developed by creator of Laravel Taylor Otwell.
It is mostly used for creating RESTful API's & microservices.
Lumen is built on top components of Laravel.

Question: How to Install Lumen via Composer?

composer create-project --prefer-dist laravel/lumen myproject

Question: List benefits of using Laravel over other PHP frameworks?

Artisan
Migrations & Seeding
Blade Template Engine
Middleware - HTTP middleware provide a convenient mechanism for filtering HTTP requests
Routing (RESTful routing)
Authentication, Cashier, Scheduler, SSH, Socialite
Security
Unit Testing
Caching

Question: Which Template Engine used by Laravel?
Blade is the simple, yet powerful templating engine provided with Laravel.

Question: How to enable maintenance mode in Laravel?

// Enable maintenance mode
php artisan down

// Disable maintenance mode
php artisan up

Question: What are Closures in Laravel?
A Closure is an anonymous function. Closures are often used as a callback methods and can be used as a parameter in a function.

Question: List out databases that laravel supports?
MySQL
PostgreSQL
SQLite
SQL Server

Question: How To Use Insert Query In Laravel?

class UserController extends Controller
{
    /**
     * Create a new user instance.
     *
     * @param  Request  $request
     * @return Response
     */
    public function store(Request $request)
    {
        $user = new User;
        $user->name = $request->name;
        $user->role = $request->role;
        $user->save();
    }

Question: What are the available Router Methods?

Route::get($uri, $callback);
Route::post($uri, $callback);
Route::put($uri, $callback);
Route::patch($uri, $callback);
Route::delete($uri, $callback);
Route::options($uri, $callback);

Question: How To Use Update Query In Laravel?

$result = User::where('id',1)->update(['name'=>'My web technology experts notes']);

Question: How To Use Delete Query In Laravel?

$result = User::where('id',$id)->delete();

Question: What is Response in Laravel?
Following are different type of responses?

View Responses
JSON Responses
File Downloads
File Responses
Response Macros
Redirecting To Named Routes
Redirecting To Controller Actions
Redirecting To External Domains
Redirecting With Flashed Session Data

Question: How to get current environment in Laravel?
$environment = App::environment();

Question: Where do you locate database configuration file?
Migrations are like version control for your database, that's allow to easily modify and share the application's database schema. Migrations are typically paired with Laravel's schema builder to easily build your application's database schema.

Question: What are laravel 6 features?

Inbuilt CRSF (cross-site request forgery ) Protection.
Inbuilt paginations
Reverse Routing
Query builder
Route caching
Database Migration
IOC (Inverse of Control) .
Job middleware
Lazy collections

Friday 3 April 2020

Laravel interview questions for 3 year experienced

Question: Explain validation in Laravel.?
ValidatesRequests is the trait which is been used by Laravel classes for validating input data.

public function store(Request $request)
{
   $validatedData = $request->validate([
       'title' => 'required|unique:posts|max:255',
       'description' => 'required',
       'email' => 'required',
   ]);
}

Question: What is CSRF protection and CSRF token?
Cross-site forgeries are a type of malicious exploit where unauthorized person/command do/run on behalf of the authenticated user.
Laravel generates a CSRF "token" automatically for each active user session.
This token is used to verify that the authenticated user is the one actually making the requests.

Question: What is Laravel Dusk?
It is expressive, easy-to-use browser automation and testing API.

Question: What is Laravel Echo?
Event broadcasting, evolved. Bring the power of WebSockets to your application without the complexity.

Question: How do you install Laravel?
Laravel utilizes Composer to manage its dependencies. So, before using Laravel, make sure we have Composer installed on your machine.

Question: Explain Binding Instances?
You may also bind an existing object instance into the container using the instance method.

$api = new HelpSpot\API(new HttpClient);
$this->app->instance("HelpSpot\API", $api);

Question: Explain Extending Bindings?

$this->app->extend(Service::class, function($service) {
    return new DecoratedService($service);
});

Question: What is the make Method?
You may use the make method to resolve a class instance out of the container.

$api = $this->app->make("HelpSpot\API");

Question: What is Register Method?
within the register method, you should only bind things into the service container.

Question: What is the Boot Method?
if we need to register a view composer within our service provider? This should be done within the boot method.

Question: Where do you regiser service providers?
config/app.php configuration file

Question: What are Laravel’s Contracts?
Laravel’s Contracts are a set of interfaces that define the core services provided by the framework.

Question: Give example of Router?

Route::get("foo", function () {
return "Hello World";
});

Question: What are the available Router Methods?

Route::get($uri, $callback);
Route::post($uri, $callback);
Route::put($uri, $callback);
Route::patch($uri, $callback);
Route::delete($uri, $callback);
Route::options($uri, $callback);

Question: How to 301 redirect in laravel (permanent redirect)

Route::redirect("/old", "/new", 301);

Question: How to 302 redirectin laravel (temporary redirect)

Route::redirect("/old", "/new", 302);

Question: What are Middleware Groups?
Sometimes you may want to group several middleware under a single key to make them easier to assign to routes.

Question: What are Redirect responses?
Redirect responses are instances of the Illuminate\Http\RedirectResponse class, and contain the proper headers needed to redirect the user to another URL.

Question: Where do you locate database configuration file?
The database configuration for your application is located at config/database.php.

Question: What are Blade Templates?
Blade is the simple, yet powerful templating engine provided with Laravel.

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