mariusGundersen

JavaScript has labels, which can be placed before blocks to create a named section of code, serving almost the same use as an imidiately invoked function expression (IIFE)

(function iife(){
  var scoped = "this is scoped stuff";
})();

iife: {
  let scoped = "this is scoped";
}

mariusGundersen

The ES6 Promise specification contains the very useful constructor for creating a promise, like so:

var promise = new Promise(function(resolve, reject){
  resolve("hi");
});

promise.then(function(message){
  console.log(message);
});

mariusGundersen

function Lazy(list, ...steps){
  this.list = list;
  this.steps = steps; 
}

Lazy.prototype.map = function(f){
  return new Lazy(this.list, ...this.steps, iteration 
    => ( for (entry of iteration) f(entry)));
}

mariusGundersen

function toHex(rgb){
  var a = /rgb\((\d+),\s*(\d+),\s*(\d+)\)/.exec(rgb).reverse();
  a.pop();
  return '#'+a.map(a => parseInt(a, 10).toString(16)).join('');
}

var variables = {
  '#747474': '#FF0000',
  '#f8b912': '#00FFBB'
};

mariusGundersen

#!/usr/bin/env bash
# MIT © Sindre Sorhus - sindresorhus.com

# git hook to run a command after `git pull` or `git checkout` if a specified file was changed
# Run `chmod +x post-checkout` to make it executable then put it into `.git/hooks/`.

changed_files="$(git diff-tree -r --name-only --no-commit-id HEAD@{1} HEAD)"

check_run() {
	echo "$changed_files" | grep --quiet "$1" && echo " * changes detected in $1" && echo " * running $2" && eval "$2"

mariusGundersen

export default class AsyncQueue {
  constructor() {
    this.items = [];
    this.receivers = [];
  }
  
  push(value) {
    if(this.receivers.length == 0){
      this.items.push(value);
    }else{

mariusGundersen

class Vector{
  constructor(x, y){
    this.x = x;
    this.y = y;
  }
  [Symbol['+']](that){
    return new Vector(this.x + that.x, this.y + that.y);
  }
  [Symbol['-']](that){
    return new Vector(this.x - that.x, this.y - that.y);

mariusGundersen

// Given the following generator that will walk a tree structure depth-first
// for each subtree it will go deeper unless the consumer returns `false`

function* depthFirst(tree, prefix=''){
  for(const [key, value] of Object.entries(tree)){
    const path = `${prefix}/${key}`;
    if(typeof value === 'string'){
      yield {path, value}
    }else{
      if(false !== (yield {path})){

mariusGundersen

async function* source(){
  let n = 1;
  while(true){
    yield n++;
    await new Promise(res => setTimeout(res, 100));
  }
}

async function* map(func){
  for await(const chunk of this){

mariusGundersen

async function run(){
  console.log('start');
  const result = await source()
    ::map(t => t*2)
    ::take(30)
    ::buffer(10)
    ::map(t => Promise.delay(Math.random()*10, t))
    ::filter(t => t%4 == 0)
    ::reduce((a, b) => a+b, 0);
  console.log('done', result);