When we run nodejs in sarver it's perticuler one thread can handel many connections.
Let suppose, I run a process which is I/O bound mean's wait for database excutor fatch so it's doesn't block thread and wait for a callback. When that particular I/O bound resolved a event fired.
What is nmp?
nmp stands for node package manager.
why use [npm init] command
This utility will walk us through creating a package.json file.
What is Expressjs?
Express is a flexible Node.js web application framework that provides a strong set of features for web and mobile applications.
How to install Express in myapp directory and save it in the dependencies list?
$ npm install express
To install Express temporarily and not add it to the dependencies list:
$ npm install express --no-save
How to uninstall express
$ npm uninstall express
What is nodemon?
nodemon is a tool that helps develop Node.js based applications by automatically restarting the node application when file changes in the directory are detected
Install nodemon in our system path globally:
$ npm install -g nodemon
Install nodemon as a development dependency:
$ npm install --save-dev nodemon
How to uninstsll?
$ npm uninstall nodemon
After download nodemon in your system if you get error like [nodemon : File C:\Users\user\AppData\Roaming\npm\nodemon.ps1 cannot be loaded because running scripts is disabled on this system. For more information, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170.]
1. Open PowerShell (Run As Administrator)
2. Check the current execution policy using this command
Get-ExecutionPolicy
# You should get 'Restricted'
3. Run this command to make it 'Unrestricted'
Set-ExecutionPolicy Unrestricted
4. Check again whether execution policy changed by running this command
Get-ExecutionPolicy
# You should get 'Unrestricted'
5. Now try to run nodemon on your project
nodemon 'filename.js'
How to import-export in CommonJS module?
From second.js to first.js
(second.js)---
function Simple(){
console.log("Hello World");
}
module.exports = Simple;
(first.js)---
const Simple = require("./second.js");
Simple();
How to use ES6 module?
STEP-1: go to package.json file and add "type":"module", after "author":"Teuton",
STEP-2: add file name with mjs (first.mjs).