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Articles by Mayank Agarwal
Page 28 of 31
Node.js – hash.copy() Method
The Hash class is one of the many utility classes that is used for creating the hash digests of data. The hash.copy() method creates a new Hash object that will contain a deep copy of the internal state of the current hash object.Syntaxhash.copy([options])Parametersoptions −This input parameter takes input to control the stream behaviour and therefore will contain the stream.tranformOptions.Example 1Create a file "hashCopy.js" and copy the following code snippet. After creating the file, use the command "node hashCopy.js" to run this code.// hash.update() demo Example // Importing the crypto module const crypto = require('crypto'); // Defining the hash ...
Read MoreDifference between NodeJS and ReactJS
ReactJS and NodeJS both are a widely used subsets of JavaScript nowadays with high performance. But both are different in someways. In the below article, we will discuss the difference between the two and which is better to use to build a web application and why ?NodeJSIt is a completely open-source and cross-platform runtime environment used for executing JavaScript code outside of a browser.The event driven model of NodeJs lets the user to create a fast and scalable network applications. First thing to remember about NodeJS is that its neither a framework and nor a programming language. NodeJS is a ...
Read MoreURLSearchParams.has & delete() in Node
Introduction to has()This function returns true or false based upon the query argument. The function will return true if name-value pair exists for the argument.Syntaxvar bool = URLSearchParams.has(name);It will return TRUE if name is present, else FALSE.ParametersThe input parameter is a name that needs to be searched in the URL.Example // Defining the URL as a constant const myURL = new URL( 'https://example.org/?firstName=John'); // Printing whether the argument exists or not console.log(myURL.searchParams.get('firstName'));OutputtrueExample// Defining the URL as a constant const myURL = new URL( 'https://example.org/?firstName=John'); // Printing whether the argument exists or not console.log(myURL.searchParams.get('lastName'));OutputfalseIntroduction to delete()It will delete/remove ...
Read MoreSync vs Async vs Async/Await in fs-extra - NodeJS
Introduction to fs-extraBefore proceeding with fs-extra, one must have a basic knowledge of the fs file system. The fs-extra is an extension of the fs file system and has more methods than it. It adds some file method systems that are not there in the naive fs modules. Fs-extra adds the promise support to the fs methods and therefore better than fs.Installationnpm install fs-extraSyntaxfs-extra is a replacement for the native fs file system. All methods that are in fs are attached to fs-extra as well. Therefore, you don't need to include fs again.const fs = require('fs-extra');Most methods provided by fs-extra ...
Read MorereadJson() function in fs-extra - NodeJS
readJson() method reads a JSON object and then parses it into an object.SyntaxreadJson(file [, options] [, callback])Parametersfile – String parameter which will contain name and location of the file holding the JSON.options – The 'outputFile' function supports the following options −encoding – Default 'null'.flag – Default 'r'. The flag 'r' opens a file for reading and an exception will occur if file does not exist.signal – allows aborting an ongoing output file functioncallback – This function will give a callback if any error occurs.Example 1Check that fs-extra is installed before proceeding; if not, install fs-exra.You can use the following command to check whether fs-extra is installed ...
Read MoreQuerying Data from Table using Node
In this article, we will see how to select or query the data from a database based on different table fields and columns.Before proceeding, please check the following steps are already executed −mkdir mysql-testcd mysql-testnpm init -ynpm install mysqlThe above steps are for installing the Node - mysql dependecy in the project folder.Select Data from Table Using NodeCreate a new file with the following name – app.jsCopy and Paste the following code snippet in this file.Now, run the following command to check the output of the above program.>> node app.jsExample// Checking the MySQL dependency – if exists var mysql = ...
Read MorepathExists() function in fs-extra - NodeJS
Introduction to Async pathExists()This method will test whether the given path exists or not by checking with the file system. It will throw error in callback if the path does not exist.SyntaxpathExists(file[, callback])Parametersfile – This is the path of the file that needs to be checked in all the file systems.callback – This function will give a callback if any error occurs.ExampleCheck that fs-extra is installed before proceeding; if not, install fs-exra.You can use the following command to check whether fs-extra is installed or not.npm ls fs-extraCreate a pathExists.js and copy-paste the following code snippet into that file.Now, run the ...
Read MoreoutputFile() function in fs-extra - NodeJS
Introduction to Async outputFile()This method is similar to write file of 'fs'. The only difference is it will create the parent directories, if not present. The argument passed should always be a file path, not a buffer or a file descriptor.SyntaxoutputFile(file, data[, options] [, callback])Parametersfile – String parameter which will contain name and location of the file.data – The data can hold a string data, buffer stream or a Unit8 string array that is to be stored.options – The 'outputFile' function supports the following options −encoding – Default 'utf8'.mode – Default 0o666signal – allown aborting an ongoing output file functioncallback ...
Read MoreNodeJS - Exception Handling in Asynchronous Code
An exception is a type of an event that occurs while executing or running a program that stops the normal flow of the program and returns to the system. When an exception occurs the method creates an object and gives it to the runtime system. This creating an exception and giving it to the runtime system is known as throwing an Exception.We need to handle these Exceptions to handle any use case and prevent the system from crashing or performing an unprecedented set of instructions. If we donot handle or throw exceptions, the program may perform strangely.Exception handling in Asynchronous ...
Read MoreHow to overlay text on an image using JIMP in NodeJS?
Like Image, we can also overlay text on an image using JIMP. This can be used to display brands or copyright information on images. The print() method is used to write text on images. Though Jimp can only support the Bitmap font format (.fnt), but other fonts can be converted into this format to be compatible and used with JIMP.Syntaximage.print(font, x, y, message);Definition of print() paramtersfont – This describes the font passed by the user for writing the text on image.x, y – The coordinates where the file will be placed.message – This is the user defined message which is passed in ...
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