To detect if argument is array instead of object with Node.js, we call the util.isArray method.
For instance, we write
const util = require("util");
const isArray = util.isArray([]);
const isArray2 = util.isArray(Array(55));
to call isArray with the value we want to check if it’s an array.
isArray should return true for both since both arguments are arrays.
To let others on a local network, access my Node.js app while it’s running on a machine, we call listen with the IP address of the computer
For instance, we write
server.listen(3000, "192.168.0.3");
to call listen with the IP address of the computer that the server is running on to allow external connections on port 3000.
To encrypt data that needs to be decrypted in Node.js, we use the crypto module.
For instance, we write
const crypto = require("crypto");
const assert = require("assert");
const algorithm = "aes256";
const key = "password";
const text = "I love kittens";
const cipher = crypto.createCipher(algorithm, key);
const encrypted = cipher.update(text, "utf8", "hex") + cipher.final("hex");
const decipher = crypto.createDecipher(algorithm, key);
const decrypted =
decipher.update(encrypted, "hex", "utf8") + decipher.final("utf8");
to create a cipher with createCipher.
Then we call cipher.update to encrypt the text string.
Next, we call createDecipher with the same algorithm and key we call createCipher with.
The we call decipher.update to decrypt the encrypted string.
To fix Uncaught TypeError: Object.values is not a function JavaScript, we can use Object.keys instead.
For instance, we write
const vals = Object.keys(countries).map((key) => {
return countries[key];
});
to get the keys from the countries object with Object.keys.
Then we call map with a callback to get the value from each key in countries and return the array of values.
To fix Mongoose: CastError: Cast to ObjectId failed for value "[object Object]" at path "_id" with Node.js, we make sure we’re casting a valid value to an object ID.
For instance, we write
const mongoose = require("mongoose");
console.log(mongoose.Types.ObjectId.isValid("53cb6b9b4f4ddef1ad47f943"));
console.log(mongoose.Types.ObjectId.isValid("whatever"));
to use the mongoose.Types.ObjectId.isValid to check if the value we’re trying to cast to an object ID is a valid value.
The first console log should log true since it’s a valid object ID value.
And the 2nd one logs false since it’s not a valid object ID value.