razorUX JS Utils

My collection of custom Node.js utilities. Small useful, and constantly improved!

• Working with environment variables
• Read/write files: plaintext, CSV, and JSON
• Normalize tokens
• Dollar /cents conversion
• Functional pipe methods
• Object cloning
• Iteration syntax sugar
• Sleep
• Enable / disable console
• Base64 encode/decode
• Insecure random numbers
• Retry network errors
• Type Assertions
• Slack messaging
• JSON caching with Memcachier

Installation

npm install razorux-js-utils

Included functions

loadEnvVars(filePath);
validateEnvVars([ ENV_VAR ]);

readCsvFile(path);
writeCsvFile(data, path);

readTextFile(path);

ensureDirExists(path);

readJsonFile(path);
writeJsonFile(data, path);

normalizeToken(string);

dollarsToCents(number);
centsToDollars(number);

invokeMethod(Function);


pipe([ function() {}, function() {} ]);
map([], function() {});
reduce([], function() {});
objectToEntries({});
entriesToObject([key, value]);

clone(Object)

asyncMap(Array, Function);
asyncForEach(Array, Function);

sendSlackNotification,
getCloudWatchLogDeeplink()
sendErrorNotification,

simpleHash(Any)

sleep(number) // (milliseconds)

parseBoolean(String);

retryable({fn, retryCount = 3, timeout = 300, addRandomDelay = true});

validateJson(json, requiredPaths);

createErrorType(name, suppressErrorNotification);

enableConsoleLogging();
disableConsoleLogging();

base64ToString,
stringToBase64

Modules

Insecure Random

const n = randomNumberBetween(0, 42);
# => a random number within range, **inclusive**

Base64

A pair of functions to encode/decode base64 strings. Works exactly as you'd expect.

const b64 = stringToBase64("Just you wait, Henry Higgins, just you wait...")
// => "SnVzdCB5b3Ugd2FpdCwgSGVucnkgSGlnZ2lucywganVzdCB5b3Ugd2FpdC4uLg=="

base64ToString(b64)
// # => "Just you wait, Henry Higgins, just you wait..."

Retry

This package includes a powerful retry function for retrying pretty much any function, including async promises.

• [x] Max retry count

• [x] Linear retry delay

• [x] Global Timeout

• [x] Truncated exponential backoff

• [x] Min and max backoff values

• [x] Jitter

• [x] Jitter min and max

• [x] Return true to break out of retry

• [] Error matchers

const {	
  retry
} = require('main');

function myAsyncFunction() { ... }

// Simple use case
await retry(myAsyncFunction);

const ONE_SECOND = 1000;
const ONE_MINUTE = 1000 * 60;

// Retry all errors with backoff + jitter
await retry(myAsyncFunction, {
	backoff: true,
	jitter: true,
	minRetryDelay: ONE_SECOND,
	maxRetryDelay: 3 * ONE_MINUTE, // No retry delay of longer than 3m
	timeout: 10 * ONE_MINUTE, // Give up after 10 minutes
});


// Full options
await retry(
myAsyncFunction,

{ 

// A function to retry
// Every time an exception is thrown, it will be
// retried, subject to the following parameters

onError = ()=>{
	// Optional. 
	// Will be passed every exception captured from `fn`
	
	// You can return `true` to break out of the retry block early
	// If you do so, `retry` will throw the error instead of retrying
},


maxRetryCount: Number.MAX_SAFE_INTEGER
// Amount of times to retry before giving up
// If, the amount of retries are exhausted, will throw a RetryLimitReachedError,
// with the original error wrapped inside it

timeout: 1000,
// Amount of milliseconds to wait between giving up.
// If the timeout expires will throw a RetryTimeoutError, with the original error wrapped inside it.
// Example: "Retry this network request until 5 minutes have passed"

// Note:
// If maxRetryCount and timeout are both set, the operation will abort
// with whichever one occurs sooner

retryDelayMs: 50,
// Amount of milliseconds to wait between retries.
// If `backoff` is true, this will be ignored

backoff: false,
// Wait exponentially more between retries
// i.e. 1000ms, 2000ms, 4000ms, 8000ms, etc.
// Perfect for rate-limited APIs

factor: 2,
// Exponent to use for backoff

minRetryDelay: 0,
// The initial delay value in milliseconds

maxRetryDelay: 1000 * 60 * 2, // Two minutes
// The maximum delay value in milliseconds.
// You should always set this to prevent the retry delay from becoming really huge


jitter: false,
// Add a randomized amount to the delay
// This is important to avoid deadlock if many instances of your program will be trying to access the same resource at once

minJitterMs:  0,
maxJitterMs:  50,
// Min and max jitter values
// Max doesn't need to be very large, just enough to break deadlock

debugLogging: false 
// Print comprehensive internal logs to the console
// Great for debugging
}) 

Caching with Memcachier

Dead-easy temporary JSON storage in Memcache.

You'll need to sign up for a free Memcachier account here.

First, make sure you've set the following environment variables:

MEMCACHIER_SERVER,
MEMCACHIER_USERNAME
MEMCACHIER_PASSWORD

# Optional. Expire cached objects after this timeout.
# Default is 12 hours
CACHE_EXPIRATION_TIMEOUT_SECONDS = 60 * 60; // 1 hour

# Optional. Shows debug logging.
# Defaults to false
MEMCACHE_LOGGING_ENABLED=true

Usage:

// JSON to store in the cache
const data = { text: "Hello World!", passenger: "Mr. Frumble" }
const key = "top_secret_key"

const cache = createCacheClient();

const storageResponse = await cache.persist(key, data);
// => true

const retrieveResponse = await cache.retrieve(key);	
// => { text: 'Hello World!', passenger: 'Mr. Frumble' }

JSON is automatically serialized and deserialized

Type Assertions

A collection of type assertions, if you need them.

• assert* functions throw an error if the value doesn't match. A match returns nothing. (The default error is TypeError. A custom error class can be used instead. )
• is* functions return true or false.

You can optionally customize the name of the error in the error message, and the error message class.

const arg = 42;

// Basic usage
assertTypeString(arg);
// => throws TypeError "Expected Argument to be a String. (Got: 42. typeof: number)"


// Customized errors
assertTypeString(arg, 'Input String', MyInputStringError);
// => throws MyInputStringError "Expected Input String to be a String. (Got: 42. typeof: number)"

Included assertions:

assertDefined(arg, argName, customErrorClass);
assertTruthy(arg, argName, customErrorClass);

assertTypeString(arg, argName, customErrorClass);
assertTypeNumber(arg, argName, customErrorClass);
assertTypeObject(arg, argName, customErrorClass);
assertTypeArray(arg, argName, customErrorClass);

isTypeof(value, typeString) //  i.e. isTypeof(42, 'number') -> true
isObject(arg);
isArray(arg);
isNull(arg);
isUndefined(arg)

Thank You

Development sponsored by razorUX