Web Technology Experts Notes

Friday, 17 March 2017

Node js Tutorial for beginners with examples - page 4

Question: How to print a stack trace in Node.js?

console.trace("print me")

Question: How can I get the full object in Node.js's console.log()?

const util = require('util');
console.log(util.inspect(myObject, false, null))

Question: How to use jQuery with Node.js?
First instal the jquery then use as following.

require("jsdom").env("", function(err, window) {
    if (err) {
        console.error(err);
        return;
    }

    var $ = require("jquery")(window);
});

Question: How to change bower's default components folder?
Create a .bowerrc file in root and add following code.

{
  "directory" : "public/components"
}

Question: How to encode base64 in nodeJS?

console.log(new Buffer("hello").toString('base64')); //aGVsbG8=

Question: How to decode base64 in nodeJS?

console.log(new Buffer("aGVsbG8=", 'base64').toString('ascii')); //hello

Question: How to get listing of files in folder?

const testFolder = './files/';
const fs = require('fs');
fs.readdir(testFolder, (err, files) => {
  files.forEach(file => {
    console.log(file);
  });
})

Question: How do you extract POST data in Node.js?

app.use(express.bodyParser());
app.post('/', function(request, response){
    console.log(request.body.user.fname);  //print first name
    console.log(request.body.user.lname); //print last name
});

Question: How to remove file nodeJS?

var fs = require('fs');
var filePath = '/folder/arun.docx'; 
fs.unlinkSync(filePath);

Question: How to access the GET parameters after ? in Express?

var email = req.param('email');

Question: How to copy file in nodeJS?

var fs = require('fs');
fs.createReadStream('existing.txt').pipe(fs.createWriteStream('new_existing.txt'));

Question: How to append string in File?

var fs = require('fs');
fs.appendFile('message.txt', 'data to append', function (err) {

});

Question: How to get version of package?

var packageJSON = require('./package.json');
console.log(packageJSON.version);

Question: What is express js?
Express.js is a NodeJS framework.
It is designed for building single-page, multi-page, and hybrid web applications.

Question: How to Send emails in Node.js?
You can use node-email-templates.
https://github.com/crocodilejs/node-email-templates

Question: How to get Ip Address of client?

request.connection.remoteAddress

//device token $deviceToken = "a58c9e7406c4b591eda8f192027d00ef82cdba361821f693e7b8ac9cb3afbc61"; //Message will send to ios device $message = 'this is custom message'; //certificate file $apnsCert = 'pushcert.pem'; //certificate password $passphrase = 1234; $ctx = stream_context_create(); stream_context_set_option($ctx, 'ssl', 'local_cert', $apnsCert); stream_context_set_option($ctx, 'ssl', 'passphrase', $passphrase); $fp = stream_socket_client('ssl://gateway.sandbox.push.apple.com:2195', $err, $errstr, 60, STREAM_CLIENT_CONNECT | STREAM_CLIENT_PERSISTENT, $ctx); // Create the payload body $body['aps'] = array( 'badge' => +1, 'alert' => $message, 'sound' => 'default' ); $payload = json_encode($body); // Build the binary notification $msg = chr(0) . pack('n', 32) . pack('H*', $deviceToken) . pack('n', strlen($payload)) . $payload; // Send it to the server $result = fwrite($fp, $msg, strlen($msg)); if (!$result) echo 'Message not delivered' . PHP_EOL; else echo 'Message successfully delivered amar' . $message . PHP_EOL; // Close the connection to the server fclose($fp);