dsernst

var swap = function (array, pos1, pos2) {
  var temp = array[pos1];
  array[pos1] = array[pos2];
  array[pos2] = temp;
};

var heapsPermute = function (array, output, n) {
  n = n || array.length; // set n default to array.length
  if (n === 1) {
    output(array);

dsernst

How to set up stress-free SSL on an OS X development machine

One of the best ways to reduce complexity (read: stress) in web development is to minimize the differences between your development and production environments. After being frustrated by attempts to unify the approach to SSL on my local machine and in production, I searched for a workflow that would make the protocol invisible to me between all environments.

Most workflows make the following compromises:

• Use HTTPS in production but HTTP locally. This is annoying because it makes the environments inconsistent, and the protocol choices leak up into the stack. For example, your web application needs to understand the underlying protocol when using the secure flag for cookies. If you don't get this right, your HTTP development server won't be able to read the cookies it writes, or worse, your HTTPS production server could pass sensitive cookies over an insecure connection.

• Use production SSL certificates locally. This is annoying

dsernst

var mergeSort = function(array) {
  if (array.length === 1) {
    return array
  } else {
    var split = Math.floor(array.length/2)
    var left = array.slice(0, split)
    var right = array.slice(split)

    left = mergeSort(left)
    right = mergeSort(right)

dsernst

function makeRotatedArrays (size) {
  var array = [];

  for (var i = 0; i < size; i++) {
    array.push(Math.floor(Math.random() * size * 2));
  }

  array = array.sort(function (a, b) {return a - b});

  var rotationMagnitude = Math.floor(Math.random() * size);

dsernst

// Starting in the top left corner of a 2×2 grid, and only being able to move to the right and down, there are exactly 6 routes to the bottom right corner.

// How many such routes are there through a 20×20 grid?

var perimeter = 1;

var routes = 1;

var move = function (x, y) {
  if (x < perimeter && y < perimeter) {

dsernst

var getIndexBelowMaxForKey = function(str, max){
  var hash = 0;
  for (var i = 0; i < str.length; i++) {
    hash = (hash<<5) + hash + str.charCodeAt(i);
    hash = hash & hash; // Convert to 32bit integer
    hash = Math.abs(hash);
  }
  return hash % max;
};

dsernst

Keybase proof

I hereby claim:

• I am dsernst on github.
• I am dsernst (https://keybase.io/dsernst) on keybase.
• I have a public key whose fingerprint is 257F 5B97 C1C5 F97A 7071 13D2 42B1 F2E6 A8B9 F8C0

To claim this, I am signing this object:

dsernst

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Description": "Setting up your own private and secure VPN. You can read instructions on our blog https://www.webdigi.co.uk/blog/2015/how-to-setup-your-own-private-secure-free-vpn-on-the-amazon-aws-cloud-in-10-minutes/ and you can follow video instructions on Youtube https://www.youtube.com/watch?v=fBBERp5CUgo",
  "Mappings": {
    "AWSInstanceType2Arch": {
      "High.Speed.VPN-Paid": {
        "InstanceType": "t2.medium"
      },
      "Standard.VPN-Free": {
        "InstanceType": "t2.micro"

dsernst

Options for a wiki using Git as the datastore

sr/git-wiki: https://github.com/sr/git-wiki

• A quick & dirty git-powered Sinatra wiki http://atonie.org/2008/02/git-wiki

• Written in rb

  git-wiki: because who needs cool names when you use git? git-wiki is a wiki that relies on git to keep pages' history and Sinatra to serve them.

dsernst

// ?id=<GOOGLE_SHEET_ID>
function doGet(request) {
  if (!request.parameter.id) {
    return ContentService.createTextOutput(JSON.stringify(new Error('no Google Sheet id set')))
      .setMimeType(ContentService.MimeType.JSON);
  }
  
  var cache = cacheNotesAndFormulas(request.parameter.id);
  
  // Return cache as JSON