bellentuck

React-Redux data management: serialization and memoized caching of derived data

Minimizing lookup times is a central problem in data management, particularly for large applications. Linear lookup time is bad. Sublinear lookup time is better. Constant lookup is ideal.

Client-side, in the context of a Redux-managed application, the problem becomes a matter of defining the shape of app state.

This article explores two avenues for better organizing such front-end state: (1) serializing data from the back end, reducing to fully-indexed state shape via utility reducers, and (2) caching data on the front end, in particular by utilizing the Reselect library in React-Redux mapStateToProps functions to create or look up "memos" of chunks of derivable data.

bellentuck

//run this in your console
for (var i = 0; i <= 3; i++) {
  setTimeout(function(){
    console.log(i); 
  }, 0); 
} 

bellentuck

function* cycleThruFnArgs(obj, fnArr) {
  while (fnArr.length > 0) {
    yield fnArr.shift().call(obj);
  }
}

function callAll(obj, args) {
  if (arguments.length < 2) throw 'Supply obj and args array';
  
  var gen = cycleThruFnArgs(obj, args);

bellentuck

// this function takes in any parameter and can tell if it's "falsy" or not.
// falsy means it's either false, 0, null, undefined, NaN, or an empty string/array/object
// see the test cases at the bottom for a clearer picture

function isFalsy(item) {
	try {
		if (
			!item                                               // handles most, like false, 0, null, etc
			|| (
				typeof item == "object" && (

bellentuck

// under Google Chrome 36

Object.prototype.toString.call([])
// "[object Array]"
Object.prototype.toString.call(function(){})
// "[object Function]"
Object.prototype.toString.call({})
// "[object Object]"
Object.prototype.toString.call(null)
// "[object Null]"

bellentuck

/*global console: true */
"use strict";
/*
A vector type
Write a constructor Vector that represents a vector in two-dimensional
space. It takes x and y parameters (numbers), which it should save to
properties of the same name.
Give the Vector prototype two methods, plus and minus, that take another vector as a parameter and return a new vector that has the sum
or difference of the two vectors’ (the one in this and the parameter) x
and y values.

bellentuck

// Firth: https://codepen.io/Universalist/post/predicates-in-javascript

(function(predicateCombinators) {
 
  // CPL predication
  
  function and(p1, p2) {
    return function(x) {
      return p1(x) && p2(x);
    }

bellentuck

copyright: mit

bellentuck

copyright: mit

bellentuck

copyright: mit