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// 29: array - `Array.from` static method

describe('`Array.from` converts an array-like object or list into an Array', () => {

  const arrayLike = {0: 'one', 1: 'two', length: 2};
  
  it('call `Array.from` with an array-like object', function() {
    const arr = Array.from(arrayLike);
    
    assert.deepEqual(arr, ['one', 'two']);

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// 63: String - `includes()`

describe('`string.includes()` finds string within another string', function() {

  describe('find a single character', function() {
    it('in a three char string', function() {
      const searchString = 'x';
      assert.equal('xyz'.includes(searchString), true);
    });
    it('reports false if character was not found', function() {

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// 34: symbol
// A symbol is a unique and immutable data type and may be used as an identifier for object properties
// read more at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol

describe('Symbol', function() {

  it('`Symbol` lives in the global scope', function(){
    const expected = Symbol;
    assert.equal(Symbol, expected);
  });

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// 47: Set - basics

describe('`Set` lets you store unique values of any type', function(){

  it('`Set` is a new global constructor function', function() {
    assert.equal(typeof Set, 'function');
  });
  
  it('every value in a set is unique', function() {
    let set = new Set();

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// 44: Map - basics

describe('`Map` is a key/value map', function(){

  it('`Map` is a new global constructor function', function() {
    assert.equal(typeof Map, 'function');
  });
  
  it('provides `new Map().set()` to add key+value pair, `get()` to read it by key', function() {
    let map = new Map();

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// 17: unicode - in strings

describe('unicode strings', () => {

  it('are \\u prefixed', () => {
    const nuclear = `\u2622`;
    assert.equal(nuclear, '☢');
  });

  it('value is 4 bytes/digits', () => {

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// 55: Number - isInteger

describe('`Number.isInteger()` determines if a value is an integer', function(){

  const isTrue = (what) => assert.equal(what, true);
  const isFalse = (what) => assert.equal(what, false);

  it('`isInteger` is a static function on `Number`', function() {
    const whatType = 'function';
    assert.equal(typeof Number.isInteger, whatType);

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// 54: Object - is

describe('`Object.is()` determines whether two values are the same', function(){

  describe('scalar values', function() {
    it('1 is the same as 1', function() {
      const areSame = Object.is(1, 1);
      assert.equal(areSame, true);
    });
    it('int 1 is different to string "1"', function() {

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// The iterator protocol defines a standard way to produce a sequence of values (either finite or infinite).
// read more at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols

// 37: iterator/iterable - array. 

describe('array is a built-in iterable object', function() {
  
  const arr = ['a', 'B', 'see'];

  describe('the iterator', function() {

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// 22: class - creation

describe('class creation', () => {

  it('is as simple as `class XXX {}`', function() {
    class TestClass {};
    
    const instance = new TestClass();
    assert.equal(typeof instance, 'object');
  });