npm - Overview

What is npm?

npm help us(developers) to share and reuse code, and makes it easy to update the code that we already shared.

Install npm

In order to install npm, just install node.js. when you install Node.js, you automatically get npm installed on your computer because npm is distributed with Node.js

Click Here to download node.js

Verify

After installation just verify that you have node.js in your machine.
                  node -v (or) npm -v

find out npm version

Good to have the npm version 8 & above. 

Use below command to update npm version

              npm install npm@latest -g 

CONVERT VS TRY_CONVERT IN SQL 2012

TRY_CONVERT - It help us to convert to specific data type, it is most similar to CONVERT(). The only difference and advantage is it will return NULL when its fail to convert into given data type. 

Eq.

Setup new angular project

Step 1 - Install npm

In order to install npm, just install node.js. when you install Node.js, you automatically get npm installed on your computer because npm is distributed with Node.js

Click Here to download node.js

After installation just verify that you have node.js in your machine.
node -v (or) npm -v

Step 2 - Install Angular CLI 

CLI - Command Line Interface.

CLI - It is a Tool, which is used to create, develop and maintain angular applications.

npm install -g @angular/cli - This is the command used to install angular CLI.

npm -v - This is command used to get version of NPM.

Create a new angular project
ng new ProjectName

command to Create a angular project

Run a Project
   Open your angular project through command prompt and then type below command to run the project

To run angular project

ng s --o 
or 
ng serve --open

--------------------------
Terminate the Job

Ctrl +C

---------------------------

Open closed document in MS SQL SERVER

We can retrieve the query even we closed our query window in SQL without saving the script.

SELECT execquery.last_execution_time AS [Date Time], execsql.text AS [Script] FROM sys.dm_exec_query_stats AS execquery

CROSS APPLY sys.dm_exec_sql_text(execquery.sql_handle) AS execsql

ORDER BY execquery.last_execution_time DESC

Above query provides a list of scripts and its time of execution in the last 24 hours. 

This will be work for all executed scripts not only a view or procedure.

isNAN function in javascript

isNAN function checks the argument and returns true if the argument is not a number else return false


Example of isNAN()

var val='04cs';

if(isNAN(val))
{
alert('this is not a number') ;
}else{
alert('this is a number') 

}


ANS : this is not a number


var value='0411';

if(isNAN(value))
{
alert('this is not a number') ;
}else{
alert('this is a number') 

}


ANS : this is a number

undefined value and null value

undefined means a variable has been declared but has not yet been assigned a value. On the other hand, null is an assignment value. It can be assigned to a variable as a representation of no value.

Also, undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object.

Unassigned variables are initialized by JavaScript with a default value of undefined. JavaScript never sets a value to null. That must be done programmatically.

undefined check not working in javascript

Checking undefined is not work when we go normal if statement, As like below

var id=$('#txt').val();

if(id != 'undefined')
{
// Our Code
}

"id" is var type, i.e mean unknown type, such as whether "id" is string, numeric, or even undefined.  
if "txt" is not defined in the page, then id's value is  undefined, so we shall check the type of operand with value.

By using "typeof" operator we resolve above issue. The "typeof" operator in JavaScript/Jquery allows you to probe the data type of its operand.

var item = 10;
alert(typeof item); This returns the type of item not value.


if(typeof id != 'undefined')
{
// Our Code
} 

I hope this will help you to resolve the problem.