JS Array Methods

// Map:
//===
// The map() method creates a new array with the results 
// of calling a provided function on every element in the calling array.

// map(currentValue, index, array)

var numbers = [1, 5, 10, 15];
var doubles = numbers.map(function(x) {
   return x * 2;
});
// doubles is now [2, 10, 20, 30]
// numbers is still [1, 5, 10, 15]

var numbers = [1, 4, 9];
var roots = numbers.map(Math.sqrt);
// roots is now [1, 2, 3]
// numbers is still [1, 4, 9]


// Reduce:
//===
// The reduce() method applies a function against an accumulator and each element 
// in the array (from left to right) to reduce it to a single value.

// arr.reduce(callback[, initialValue])

var total = [0, 1, 2, 3].reduce(function(sum, value, i) {
  return sum + value;
}, 0);
// total is 6

var flattened = [[0, 1], [2, 3], [4, 5]].reduce(function(a, b, i) {
  return a.concat(b);
}, []);
// flattened is [0, 1, 2, 3, 4, 5]


// Includes
var myArray = [1, 2, 3, 4, 5];
myArray.includes(1) // true

// filter

// lastIndexOf

// slice(begin, end)

// some()

// every()

// toString()

// join()

// pop()

// slice(begin, end) - does not modify original array

// splice(start, deleteCount) - modifies original array

// sort() - sort happens in place, no array copy made. will not sort numbers. You must run arr.sort(function(a, b){ return a-b; }) OR arr.sort((a,b)=> a-b)

// sum all elements in an array

JS Number Methods

Number.isInteger(x)

JS Set

JS String Methods

// charAt

// toUpperCase

// repeat

// substr

// substring

// split

// charCodeAt