Array

var fruits = ['Apple', 'Banana'];

console.log(fruits.length);
// 2

var first = fruits[0];
// Apple

var last = fruits[fruits.length - 1];
// Banana

fruits.forEach(function(item, index, array) {
  console.log(item, index);
});
// Apple 0
// Banana 1

var newLength = fruits.push('Orange');
// ["Apple", "Banana", "Orange"]

var last = fruits.pop(); // remove Orange (from the end)
// ["Apple", "Banana"];

var first = fruits.shift(); // remove Apple from the front
// ["Banana"];

var newLength = fruits.unshift('Strawberry') // add to the front
// ["Strawberry", "Banana"];

fruits.push('Mango');
// ["Strawberry", "Banana", "Mango"]

var pos = fruits.indexOf('Banana');
// 1

var removedItem = fruits.splice(pos, 1); // this is how to remove an item
                                        
// ["Strawberry", "Mango"]

var vegetables = ['Cabbage', 'Turnip', 'Radish', 'Carrot'];
console.log(vegetables); 
// ["Cabbage", "Turnip", "Radish", "Carrot"]

var pos = 1, n = 2;

var removedItems = vegetables.splice(pos, n); 
// this is how to remove items, n defines the number of items to be removed,
// from that position(pos) onward to the end of array.

console.log(vegetables); 
// ["Cabbage", "Carrot"] (the original array is changed)

console.log(removedItems); 
// ["Turnip", "Radish"]

var shallowCopy = fruits.slice(); // this is how to make a copy
// ["Strawberry"]

[element0, element1, ..., elementN]
new Array(element0, element1[, ...[, elementN]])
new Array(arrayLength)

var arr = ['this is the first element', 'this is the second element'];
console.log(arr[0]);              // logs 'this is the first element'
console.log(arr[1]);              // logs 'this is the second element'
console.log(arr[arr.length - 1]); // logs 'this is the second element'

console.log(arr.0); // a syntax error

var years = [1950, 1960, 1970, 1980, 1990, 2000, 2010];
console.log(years.0);   // a syntax error
console.log(years[0]);  // works properly

renderer.3d.setTexture(model, 'character.png');     // a syntax error
renderer['3d'].setTexture(model, 'character.png');  // works properly

console.log(years['2'] != years['02']);

var promise = {
  'var'  : 'text',
  'array': [1, 2, 3, 4]
};

console.log(promise['var']);

var fruits = [];
fruits.push('banana', 'apple', 'peach');

console.log(fruits.length); // 3

fruits[5] = 'mango';
console.log(fruits[5]); // 'mango'
console.log(Object.keys(fruits));  // ['0', '1', '2', '5']
console.log(fruits.length); // 6

fruits.length = 10;
console.log(Object.keys(fruits)); // ['0', '1', '2', '5']
console.log(fruits.length); // 10

fruits.length = 2;
console.log(Object.keys(fruits)); // ['0', '1']
console.log(fruits.length); // 2

// Match one d followed by one or more b's followed by one d
// Remember matched b's and the following d
// Ignore case

var myRe = /d(b+)(d)/i;
var myArray = myRe.exec('cdbBdbsbz');

function isLetter(character) {
  return character >= 'a' && character <= 'z';
}

if (Array.prototype.every.call(str, isLetter)) {
  console.log("The string '" + str + "' contains only letters!");
}

if (Array.every(str, isLetter)) {
  console.log("The string '" + str + "' contains only letters!");
}

if (Array.from(str).every(isLetter)) { 
  console.log("The string '" + str + "' contains only letters!"); 
}

var msgArray = [];
msgArray[0] = 'Hello';
msgArray[99] = 'world';

if (msgArray.length === 100) {
  console.log('The length is 100.');
}

var board = [ 
  ['R','N','B','Q','K','B','N','R'],
  ['P','P','P','P','P','P','P','P'],
  [' ',' ',' ',' ',' ',' ',' ',' '],
  [' ',' ',' ',' ',' ',' ',' ',' '],
  [' ',' ',' ',' ',' ',' ',' ',' '],
  [' ',' ',' ',' ',' ',' ',' ',' '],
  ['p','p','p','p','p','p','p','p'],
  ['r','n','b','q','k','b','n','r'] ];

console.log(board.join('\n') + '\n\n');

// Move King's Pawn forward 2
board[4][4] = board[6][4];
board[6][4] = ' ';
console.log(board.join('\n'));

R,N,B,Q,K,B,N,R
P,P,P,P,P,P,P,P
 , , , , , , , 
 , , , , , , , 
 , , , , , , , 
 , , , , , , , 
p,p,p,p,p,p,p,p
r,n,b,q,k,b,n,r

R,N,B,Q,K,B,N,R
P,P,P,P,P,P,P,P
 , , , , , , , 
 , , , , , , , 
 , , , ,p, , , 
 , , , , , , , 
p,p,p,p, ,p,p,p
r,n,b,q,k,b,n,r

values = [];
for (var x = 0; x < 10; x++){
 values.push([
  2 ** x,
  2 * x ** 2
 ])
};
console.table(values)

0	1	0
1	2	2
2	4	8
3	8	18
4	16	32
5	32	50
6	64	72
7	128	98
8	256	128
9	512	162