Applications running in Node.js will generally experience four categories of errors: Standard JavaScript errors such as: EvalError: thrown when a call to eval() fails. SyntaxError: thrown in response to improper JavaScript language syntax. RangeError: thrown when a value is not within an expected range ReferenceError: thrown when using undefined variables TypeError: thrown when passing arguments of the wrong type URIError: thrown when a global URI handling function is misused. System err

dns.reverse(ip, callback) Performs a reverse DNS query that resolves an IPv4 or IPv6 address to an array of hostnames. The callback function has arguments (err, hostnames), where hostnames is an array of resolved hostnames for the given ip. On error, err is an Error object, where err.code is one of the DNS error codes.

crypto.getCiphers() Returns an array with the names of the supported cipher algorithms. Example: const ciphers = crypto.getCiphers(); console.log(ciphers); // ['aes-128-cbc', 'aes-128-ccm', ...]

assert.ifError(value) Throws value if value is truthy. This is useful when testing the error argument in callbacks. const assert = require('assert'); assert.ifError(0); // OK assert.ifError(1); // Throws 1 assert.ifError('error') // Throws 'error' assert.ifError(new Error()); // Throws Error

zlib.createDeflateRaw(options) Returns a new DeflateRaw object with an options.

fs.futimesSync(fd, atime, mtime) Synchronous version of fs.futimes(). Returns undefined.

util.isBuffer(object) Stability: 0 - Deprecated: Use Buffer.isBuffer() instead. Returns true if the given "object" is a Buffer. Otherwise, returns false. const util = require('util'); util.isBuffer({ length: 0 }) // false util.isBuffer([]) // false util.isBuffer(new Buffer('hello world')) // true

buf.writeUInt32BE(value, offset[, noAssert])

emitter.emit(eventName[, arg1][, arg2][, ...]) Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each. Returns true if the event had listeners, false otherwise.

Class: ChildProcess Instances of the ChildProcess class are EventEmitters that represent spawned child processes. Instances of ChildProcess are not intended to be created directly. Rather, use the child_process.spawn(), child_process.exec(), child_process.execFile(), or child_process.fork() methods to create instances of ChildProcess.