branneman

Primitive Types & Reference Types in JavaScript

An explanation of JavaScript's pass-by-value, which is unlike pass-by-reference from other languages.

Facts

• JavaScript has 2 kinds of variable types: primitive and reference.
• A fixed amount of memory is reserved after creation of every variable.
• When a variable is copied, it's in-memory value is copied.
• Passing a variable to a function via a call also creates a copy of that variable.

Primitive Types

branneman

const { curryN, curry } = require('./curry') // https://gist.github.com/branneman/4ffb7ec3fc4a2091849ba5d56742960c

// Array
const nth = curry((key, list) => list[key])
const slice = curry((from, to, list) => list.slice(from, to))
const head = nth(0)
const init = slice(0, -1)
const tail = slice(1, Infinity)
const last = slice(-1, Infinity)
const reverse = list => list.slice().reverse()

branneman

const stat = require('fs').statSync;
const AdmZip = require('adm-zip');

/**
 * Example usage
 */
newArchive(`test-${+new Date}.zip`, [
    'index.js',
    'package.json',
    'node_modules'

branneman

const curryN = (fn, arity, accIn = []) => (...args) => {
  const len = args.length
  const accOut = accIn.concat(args)
  if (len + accIn.length >= arity) {
    return fn.apply(this, accOut)
  }
  return curryN(fn, arity, accOut)
}

const curry = fn => curryN(fn, fn.length)

branneman

Better local require() paths for Node.js

Problem

When the directory structure of your Node.js application (not library!) has some depth, you end up with a lot of annoying relative paths in your require calls like:

const Article = require('../../../../app/models/article');

Those suck for maintenance and they're ugly.

Possible solutions

branneman

/**
 * Turing Machine Interpreter
 *
 * Features:
 *  - Infinite tape, both ways
 *  - Uses JS values, anything that matches ==, is a valid symbol
 *
 * Definition:
 *  - States (Q): { integer, halt }
 *  - Input symbols read/write (Σ): any integer or string

branneman

export {
  isNull,
  isUndef,
  isBool,
  isNum,
  isInt,
  isStr,
  isArr,
  isObj,
  isFunc,

branneman

var net = require('net');

//
// Client
//

function openSocket() {
    var socket = net.connect(3e3);
    socket.setKeepAlive(true);
    socket.on('connect', onConnect.bind({}, socket));

branneman

// :: (String, String) => String
const spawn = require('child_process').spawnSync;

// :: String => [String]
const getRules = raw => raw
    .split('\n')
    .map(line => line.trim())
    .filter(line => !!line)
    .filter(line => line[0] !== '/' && line[0] !== '✖')
    .map(line => line.match(/[a-z-]+$/)[0]);

branneman

#!/usr/bin/env node

'use strict';

var spawn = require('child_process').spawn;

var args = [
  '--harmony',
  'app/bootstrap.js'
];