To differentiate clients with webSocketServer in Node.js, we canm use the sec-websocket-key header.
For instance, we write
wss.on("connection", (ws, req) => {
ws.id = req.headers["sec-websocket-key"];
//...
});
to listen to the connection event with on.
And we get the sec-websocket-key header with req.headers["sec-websocket-key"] in the event handler to get the client’s ID.
To write objects into file with Node.js, we call the writeFileSync method.
For instance, we write
fs.writeFileSync("./data.json", JSON.stringify(obj, null, 2), "utf-8");
to call the writeFileSync method to write the stringified obj object to data.json.
We convert obj to a JSON string with JSON.stringify.
To get raw request body using Express with Node.js, we use the req.body property.
For instance, we write
const bodyParser = require("body-parser");
app.use(bodyParser.raw(options));
app.get(path, (req, res) => {
console.log(req.body);
//...
});
to call app.get to create a route handler for the path path.
Then we get the request body with req.body.
req.body is a buffer object.
We use the bodyParser.raw middleware to parse the request body into a buffer.
To fix missing write access in mac to the /usr/local/lib/node_modules folder on Mac, we’ve to set the folder’s owner to the current user.
For instance, we run
sudo chown -R $USER ~/.npm
sudo chown -R $USER /usr/lib/node_modules
sudo chown -R $USER /usr/local/lib/node_modules
to run chown to set the owner of the ~/.npm, /usr/lib/node_modules and the /usr/local/lib/node_modules folders to the current user.
To find user by username LIKE value with Mongoose.js and JavaScript, we use the findOne method with a regex.
For instance, we write
const name = "Peter";
model.findOne({ name: new RegExp("^" + name + "$", "i") }, (err, doc) => {
//...
});
to call findOne to find the document with field name like the 'Peter' by setting name to a regex with name in it.
We use the i flag to search in a case insensitive manner.
We get result from doc in the callback.