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+Extras
+
+- https://stackoverflow.com/questions/36022926/what-do-the-save-flags-do-with-npm-install
+  `npm i <package_name> --save` and  `npm i <package_name> ` are same now and they also update dependencies of package too. to not update dependencies of package use  `npm i <package_name> --no-save`
+
+- nvm(Node version manager)
+    `curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.1/install.sh | bash`  
+       
+    `nvm ls-remote` : for getting list of available versions which can be downloaded  
+    `nvm list` : for getting list of downloaded versions of node  
+    `nvm install 14.0.0` : for downloading and installing version 14.0.0  
+    `nvm use 14.0.0` : switching to version 14.0.0  
+    `nvm use system`: switching to version when nodejs first installed
+	`nvm alias default 18.0`: this will make 18 as default
+	
+- https://github.com/ishtms/learn-nodejs-hard-way (without installing other frameworks)
+- https://youtu.be/Nh-252u80F4 : get wifi password
+- Running nodejs in background
+  https://sentrytwo.com/92df06609b
+- To avoid running sudo
+  Why You Should Never Run "sudo npm"...   https://www.youtube.com/watch?v=aFrR56sqC_A
+- **pm2**
+   PM2 is a production process manager for Node.js applications with a built-in load balancer. It allows you to keep applications alive forever, to reload them without downtime and to facilitate common system admin tasks.
+   install this npm package globally or locally.
+   `npm i -g pm2`
+   Using this we can start multiple node instances with single command. But first starting node application instances in background
+   `pm2 start app.js --name app1` same as `node app.js` but in background
+   to stop node instance use `pm2 stop app1`
+   multiple node instance in file `ecosystem.config.js`
+   ```js
+  module.exports = {
+	  apps: [
+		{
+		  name: 'main',
+			
+		  script: 'index.js',
+		  watch: true,
+		  env: {
+			NODE_ENV: 'production',
+			PORT: 8081
+		  }
+		},
+		{
+		  name: 'ytdownloadspace',
+		  script: '../ytDownloadSpace/app.js',
+		  watch: true,
+		  env: {
+			NODE_ENV: 'production',
+			PORT: 8080
+		  }
+		},
+		{
+		  name: 'ytdlApi',
+		  script: '../ytdlApi/app.js',
+		  watch: true,
+		  env: {
+			NODE_ENV: 'production',
+			PORT: 8083
+		  }
+		}
+	  ]
+  };
+
+	```
+	and fiannly when use 
+	`pm2 start ecosystem-config.js`.
+	To stop all these started with this file use
+	`pm2 stop ecosystem-config.js`
+	To list processes use
+	`pm2 list`
+- installing packages through repo link
+  `npm i https://github.com/expressjs/express`
+  https://www.pluralsight.com/resources/blog/guides/install-npm-packages-from-gitgithub
+&nbsp;
+
+- download a file with https and fs module
+  ```js
+  const https = require("https"); // Use 'http' for non-HTTPS links
+	const fs = require("fs");
+	
+	const fileUrl =
+	  "https://cdn.discordapp.com/attachments/1473231612341915668/1473231989501853819/packages_sorted2.txt?ex=699575b5&is=69942435&hm=66884969a27901525409ff1e5400619ea5305667a130476b7982e041c55297e8&"; // Replace with your file URL
+	const destinationPath = "./downloaded-file.txt"; // Replace with desired local path and filename
+	
+	const file = fs.createWriteStream(destinationPath);
+	
+	https
+	  .get(fileUrl, (response) => {
+	    // Check if the request was successful (status code 200)
+	    if (response.statusCode !== 200) {
+	      console.error(`Download failed, status code: ${response.statusCode}`);
+	      file.close(); // Close the write stream
+	      fs.unlink(destinationPath, () => {}); // Delete the partial file
+	      return;
+	    }
+	
+	    // Pipe the response stream to the file stream
+	    response.pipe(file);
+	
+	    // Event listener for when the download is complete
+	    file.on("finish", () => {
+	      file.close();
+	      console.log("Download Completed!");
+	    });
+	  })
+	  .on("error", (err) => {
+	    // Handle network errors
+	    fs.unlink(destinationPath, () => {}); // Delete the partial file on error
+	    console.error("Error during download:", err.message);
+	  });
+	
+  ```
+
+
+&nbsp;
+
+
+tips
+1. to prevent adding of installed packages in package.json use `--no-save` flag when installing packages. eg: `npm i --no-save sqlite3`
+&nbsp;
+
+&nbsp;
+better-sqlite guide
+https://www.w3resource.com/sqlite/snippets/better-sqlite3.php
+[Comprehensive Guide to Better-SQLite3 (16_5_2026 5：48：16 am).html](../../../_resources/Comprehensive%20Guide%20to%20Better-SQLite3%20%2816_5_2026%205.html)
+for parameterized query, string concatenation using `||`
+```js
+ selectQuery = `select * from ${songDataTableEnums.tablename}
+     where ${songDataTableEnums.columns.songname} like  ? || '%' or ${songDataTableEnums.columns.songname} like  '% '|| ? || '%'
+    or ${songDataTableEnums.columns.artist_name} like  ? || '%' or ${songDataTableEnums.columns.artist_name} like  '% '|| ? || '%'`;
+```
+
+&nbsp;
+
+generate thumbnails of video
+```js
+const ffmpeg = require('fluent-ffmpeg');
+
+ffmpeg('path/to/video.mp4')
+  .screenshots({
+    count: 1,
+    timemarks: ['00:00:02'], // Capture at 2 seconds
+    filename: 'thumbnail.png',
+    folder: 'output/path/'
+  });
+
+```
+or
+```js
+ffmpeg('input.mp4')
+  .screenshots({
+    count: 3,                          // Number of screenshots to take
+    timestamps: ['10%', '30sec', 60], // Locations: percentages, strings, or numbers (seconds)
+    filename: 'thumbnail-at-%s-seconds.png', // %s inserts the timestamp
+    folder: './output',                // Destination directory
+    size: '320x240'                    // Rescales output width x height
+  })
+  .on('end', () => {
+    console.log('Screenshots taken successfully!');
+  })
+  .on('error', (err) => {
+    console.error('An error occurred: ' + err.message);
+  });
+```
+
+
+* count: Total number of images to generate. If timestamps is not provided, it automatically distributes screenshots evenly across the video duration. 
+* timestamps: An array specifying exact positions to snapshot.
+* Numbers represent absolute seconds (e.g., 15).
+   * Strings format time as HH:MM:SS.milli or specific counts (e.g., '00:01:20').
+   * Percentages evaluate relative to video length (e.g., '50%'). 
+* folder: Path to the directory where files will save. 
+* filename: Format for file naming. Use %s to interpolate the specific frame's timestamp or %i for the index sequence. 
+
+