shaunwallace

"use strict";

(() => {
  const root = document.querySelector("#root");
  const docFragment = document.createDocumentFragment();
  const arraySize = 100;
  const items = Array.from(Array(arraySize).keys());

  const options = {
    root: null,

shaunwallace

// eg (123) 456-7890
formatter(s) {
    // strip out all formatting that exists on the string
    const tel = s.replace(/[(\-)\s]/g, '');
    // if there is nothing after sanitizing or non-numeric characters
    // were entered then simply return the current state
    if (!tel) {
      return { tel: '' };
    } else if (tel.match(/[^.\d]/g)) {
      return this.state;

shaunwallace

typeof 'foo'; // "string"
typeof 42; // "number
typeof {}; // "object"
typeof true; // "boolean"
typeof null; // "object"
typeof undefined; // "undefined"
typeof () => {}; // "function"
typeof []; // "object"
typeof Symbol(); // "symbol"

shaunwallace

var person = { kind : ‘person’ };
var shaun = Object.create(person);

person.isPrototypeOf(shaun); // true

person.kind // 'person'
shaun.kind // 'person'

shaun.sayHello = function(){ console.log(‘Hello’) };

shaunwallace

JSON.stringify({foo : true, bar : false}); // returns "{"foo":true,"bar":false}"
JSON.stringify([1, "false", false]); // returns "[1,"false",false]" note the last false is not surrounded by quotes

JSON.stringify({ a: 2 }, null, " "); // returns '{\n "a": 2\n}'
JSON.stringify({ a: 2 }, null, 4); // returns '{\n    "a": 2\n}'

function replacer(k,v) {
    if( typeof v === "string") return;
    if( typeof v === "number") return 2*v;
    return v;    

shaunwallace

JSON.parse('{"foo" : "true", "bar" : "false"}'); // returns Object { foo : true, bar : false }

// returns Object {p: 10}
JSON.parse('{"p": 5}', function (k, v) {
    if(k === "") return v; // if topmost value, return it,
    return v * 2; // else return v * 2.
}); 

shaunwallace

function isBigEnough(element, index, array) {
    return element >= 10;
}

var passed = [2, 5, 8, 1, 4].some(isBigEnough); // passed is false
passed = [12, 5, 8, 1, 4].some(isBigEnough); // passed is true

shaunwallace

// will return 15
[1,2,3,4,5].reduceRight(function(previousValue, currentValue){
    return previousValue + currentValue;
});

// will return 25 since we passed in the initial value
[1,2,3,4,5].reduceRight(function(previousValue, currentValue){
    return previousValue + currentValue;
}, 10);

shaunwallace

// will return 15
[1,2,3,4,5].reduce(function(previousValue, currentValue){
    return previousValue + currentValue;
});

// will return 25 since we passed in the initial value
[1,2,3,4,5].reduce(function(previousValue, currentValue){
    return previousValue + currentValue;
}, 10);

shaunwallace

// iterating through a collection of elements returned by querySelectorAll
var elems = document.querySelectorAll('select option:checked');
var values = [].map.call(elems, function(obj) {
    return obj.value;
});

// reverse a string
var str = '12345';
[].map.call(str, function(x) {
    return x;