| // set-up a connection between the client and the server | |
| var socket = io.connect(); | |
| // let's assume that the client page, once rendered, knows what room it wants to join | |
| var room = "abc123"; | |
| socket.on('connect', function() { | |
| // Connected, let's sign-up for to receive messages for this room | |
| socket.emit('room', room); | |
| }); |
This is the simplest implementation you will find for a client/server WebSockets architecture using socket.io.
To see a full explanation, read my answer on SO here: https://stackoverflow.com/a/24232050/778272.
If you're looking for examples using frameworks, check these links:
| // based from https://github.com/justadudewhohacks/opencv4nodejs/tree/master/examples/simpleTracking1.js | |
| // This code is meant to be run on a Raspberry Pi 3 with the picamera. | |
| // NOTE: Before running this code, for OpenCV to detect the camera, you need to run sudo modprobe bcm2835-v4l2 | |
| // TODO: Write each detected frame to an image file somewhere, with the timestamp in the name | |
| const cv = require('opencv4nodejs'); | |
| const delay = 50; | |
| const hog = new cv.HOGDescriptor(); | |
| hog.setSVMDetector(cv.HOGDescriptor.getDefaultPeopleDetector()); |
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <title>Hello World!</title> | |
| </head> | |
| <body> | |
| <h1>Hello World!</h1> | |
| <!-- All of the Node.js APIs are available in this renderer process. --> | |
| We are using Node.js <script>document.write(process.versions.node)</script>, |
TLDR: Use for...of instead of forEach in asynchronous code.
Array.prototype.forEach is not designed for asynchronous code. (It was not suitable for promises, and it is not suitable for async-await.)
For example, the following forEach loop might not do what it appears to do:
| /** | |
| * Module dependencies. | |
| */ | |
| var express = require('express'), | |
| mongoStore = require('connect-mongo')(express), | |
| flash = require('connect-flash'), | |
| viewHelpers = require('./middlewares/view'), | |
| fs = require('fs'), | |
| upload = require('jquery-file-upload-middleware'); |
| // Based on http://stackoverflow.com/a/20434019 | |
| function calculateAccuracy(txPower, rssi) { | |
| if (rssi === 0) { | |
| return -1; // if we cannot determine accuracy, return -1. | |
| } | |
| var ratio = rssi * 1 / txPower; | |
| if (ratio < 1.0) { | |
| return Math.pow(ratio, 10); |
| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <title>HMAC-SHA256 Example</title> | |
| </head> | |
| <body> | |
| <script src="http://crypto.stanford.edu/sjcl/sjcl.js"></script> | |
| <script> | |
| var sharedSecret, query, signature, hmac, xhr; |
| // None of the tutorals could help me, so I adapted a few codes. | |
| // What I really want is make a full duplex way between NodeJS and Java, using encrypt/decrypt with AES 128 bit | |
| // 1 - you must have to generate the key | |
| openssl enc -aes-128-cbc -k secret -P -md sha1 | |
| // key examples: | |
| // DCDD74627CD60252E35DFBA91A4556AA | |
| // 2CB24CFDB3F2520A5809EB4851168162 | |
| // 468CA14CA44C82B8264F61D42E0E9FA1 |