有段时间没有做前端页面，最近复习了下前端的知识，同时发现大家都已经进入ES6开发的节奏了，前端果然善变啊。看完es6，发现这货跟java越来越像了，不是指名字。
http://es6katas.org/
Promise
easybasics
creation
chaining then()
the API
newpromise.catch()
Array
Array.from()
Array.of()
[].fill()
[].find()
[].findIndex()
[].entries()
[].keys()
[].values()
Class
easycreation
accessors
easystatic
easyextends
more extends
super in method
super in constructor
Destructuring
easyarray
easystring
easyobject
easydefaults
parameters
assign
Generator
creation
iterator
yield expressions
send value to a generator
send function to a generator
return inside a generator function
Map
easyBasics
map.get()
map.set()
initialize
easymap.has()
Reflect
easyBasics
Reflect.apply()
Reflect.getPrototypeOf()
Reflect.construct()
Reflect.defineProperty()
Set
basics
set.add()
easyset.delete()
easythe API
easyset.clear()
Iterator
array
string
protocol
usage
Object literal
basics
computed properties
easygetter
easysetter
String
easystring.includes()
easystring.repeat(count)
easystring.startsWith()
easystring.endsWith()
Template strings
easybasics
easymultiline
tagged template strings
raw property
Symbol
basics
Symbol.for()
Symbol.keyFor()
Arrow functions
easybasics
easyfunction binding
Block scope
easylet declaration
easyconst declaration
Rest operator
as parameter
with destructuring
Spread operator
with arrays
with strings
Default parameters
easyBasics
Modules
easyimport statement
Number
easyNumber.isInteger()
Object
easyObject.is()
Unicode
in strings