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Node.js Articles
Page 10 of 22
Node.js – Process beforeExit Event
The 'beforeExit' event is called when Node.js empties its event loop and has no other work to schedule. The Node.js process exits normally when there is no work scheduled but a listener registered on the 'before exit' event can make async calls and thereby cause the Node.js process to continue.Example 1Create a file with the name "beforeExit.js" and copy the following code. After creating the file, use the command "node beforeExit.js" to run this code as shown in the example below −// process 'beforeExit' Demo Example // Importing the process module const process = require('process'); // Calling the ...
Read MoreNode.js – diffieHellman.getGenerator() Method
The diffieHellman.getGenerator() method returns the Diffie-Hellman generator in the specified encoding. A string is returned in case an encoding is passed, else a buffer is returned.SyntaxdiffieHellman.getGenerator([encoding])Parametersencoding - This parameter specifies the encoding of the return value.Example 1Create a file with the name "generator.js" and copy the following code. After creating the file, use the command "node generator.js" to run this code as shown in the example below:// diffieHellman.getPrime() Demo Example // Importing cryptoDiffieHellman from the crypto module const { createDiffieHellman } = require('crypto'); // Initializing the diffieHellman object const dh = createDiffieHellman(512); // Generate DiffieHellman's Generator ...
Read MoreNode.js – dnsPromises.resolveAny() Method
The dnsPromises.resolveAny() method uses the DNS protocol to resolve all records (this is also known as ANY or * query). The promise is resolved with an array containing various types of records.TypeProperties'A'IPv4 address'AAAA'IPv6 address'Any'Any RecordsMXMail Exchange RecordsNAPTRName authority pointer recordsNSName server recordsPTRPointer RecordsSOAStart of Authority RecordsSRVService RecordsTXTText RecordsCNAMECanonical Name RecordsSyntaxdnsPromises.resolveAny(hostname)Parametershostname - This parameter takes input for the hostname to be resolved.Example 1Create a file with the name "resolveAny.js" and copy the following code. After creating the file, use the command "node resolveAny.js" to run this code, as shown in the example below −// Node.js program to demonstrate the // dnsPromises.resolveAny() method ...
Read MoreNode.js – process.throwDeprecation() Method
This method indicates about the flag value of --throw-deprecation which is set to True or False on the current Node.js project.The process.throwDeprecation() method is mutable, so the deprecation warning results in errors may be altered at runtime.Syntaxprocess.throwDeprecation( )Example 1Create a file with the name "throwDeprecation.js" and copy the following code. After creating the file, use the command "node throwDeprecation.js" to run this code as shown in the example below// process.throwDeprecation() Demo Example // Importing the process module const process = require('process'); // Printing the --throw-Deprecation default value console.log(process.throwDeprecation);Output 1undefinedOutput 2trueExample 2Let's take another example// process.throwDeprecation() Demo Example ...
Read MoreNode.js – dns.resolve4() Method
The dns.resolve4() method uses the DNS protocol to resolve a IPv4 address for the hostname. The arguments passed to the callback function can contain an array of multiple addresses.Syntaxdns.resolve4(hostname, [options], callback)Parametershostname - This parameter takes input for the hostname to be resolved.options - It can have the following optionsttl - It defines the Time-To-Live (TTL) for each record. Callback receives an array of addresses like this{ address: '1.2.3.4', ttl:60 }callback - It will catch errors, if any.Example 1Create a file with the name "resolve4.js" and copy the following code snippet. After creating the file, use the command "node resolve4.js" to ...
Read MoreNode.js – Immediate Timer Class
The Immediate Timer class is used for scheduling the functions that we need to call at a certain period of time in future. These tasks can be scheduled by using the Immediate timer class and using the setImmediate() method. The Immediate class has an object for setImmediate() method and it passes the same object to clearImmediate() in case it wants to cancel the scheduled timer function.Given below are the Immediate class ref objects −1. immediate.ref()This method is called if the immediate object is active for too long and did not exit.Syntaximmediate.ref()2. immediate.unref()This object keeps the event loop ‘active’ until False ...
Read MoreNode.js – diffieHellman.getPublicKey() Method
The diffieHellman.getPublicKey() returns the Diffie-Hellman generated public key that is specified by the encoding passed. It will return a string in case the encoding is passed, else it will return a buffer.SyntaxdiffieHellman.getPublicKey([encoding])Parametersencoding – This parameter specifies the encoding of the return value.Example 1Create a file with the name "publicKey.js" and copy the following code snippet. After creating the file, use the command "node publicKey.js" to run this code.// diffieHellman.getPublicKey() Demo Example // Importing the crypto module const crypto = require('crypto') // Initializing the diffieHellman const dh = crypto.createDiffieHellman(512); // Taking default publicKey as null let publicKey = ...
Read MoreNode.js – Timeout-hasRef() & Timeout-refresh() methods
The Timeout object is internally created and is returned from the setTimeout() and setInterval() method. You can use this object and pass it to either clearTimeout() or clearInterval() methods in order to cancel the scheduled actionsFollowing are the timeout class ref objects that can be used to control the default behaviour1. timeout.hasRef()This method keeps the node event loop active as long as its value is True.Syntaxtimeout.hasRef()2. timeout.refresh()This method refreshes the timer’s start time to the current time and reschedules the timer to its callback where the previously specified duration will be adjusted to the current time. This method helps in ...
Read MoreNode.js – process.channel Property
When a node process is spawned with an IPC channel, the process.channel property provides the reference to that IPC channel. If no IPC channel exists, this property is then undefined.Syntaxprocess.channelExample 1Create two files "channel.js" and "util.js" and copy the following code snippets. After creating the files, use the commands "node channels.js" and "node util.js" to run the codes.channel.js// process.channel Property Demo Example // Importing the process modules const cp = require('child_process'); // Getting reference to the child const process = cp.fork(`${__dirname}/util.js`); // Sending the below message to child process.send({ msg: 'Welcome to Tutorials Point' }); console.log(process.channel)util.js// ...
Read MoreNode.js – dnsPromises.resolve4() Method
The dnsPromises.resolve4() method uses the DNS protocol to resolve IPv4 addresses (A records) for the hostname. A promise is resolved with an array of IP addresses when True.The difference between the dnsPromises and dns module is that dnsPromises provides an alternative way to asynchronous DNS methods that return Promise objects instead of callbacks.Syntaxdns.resolve4(hostname, [options])Parametershostname – This parameter takes input for hostname to be resolved.options – It can have the following options −ttl – This defines the Time-To-Live (TTL) for each record. Callback receives an array of addresses like this – { address: ‘1.2.3.4’, ttl:60 }Example 1Create a file "resolve4.js" and ...
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