JS interview question - what is the difference between Es5 and ES6?

ES5 and ES6 What's the difference? ？
ES6 Some new technologies have been added :
1、let Declare variables and const declare constant , Both have block level scopes ES5 There is no block level scope in , also var There is variable Promotion , stay let in , The variables used must be declared
2、 Arrow function ES6 The function definition in no longer uses the keyword function(), It's using ()=> To define
3、 Template string Template strings are enhanced strings , Use back quotes （`） identification , It can be used as a normal string , It can also be used to define multiline strings
4、 Deconstruct assignment ES6 Allow to follow certain mode , Extract values from arrays and objects , Assign values to variables
5、for of loop for…of Loops can traverse arrays 、Set and Map structure 、 Some array like objects 、 object , And strings
6、import、export Import and export ES6 In the standard ,Js Native support module . take JS Code is divided into small pieces with different functions for modularization , Write the codes of different functions in different files , Each module only needs to export the common interface part , Then it can be used in other places by importing modules
7、set and Map Set data structure , It's like an array . All the data is unique , There are no duplicate values . It's itself a constructor ;Map Is the structure of a set of key value pairs , With extremely fast search speed . It consists of set Method to store data ,get Method to retrieve data .
8、… Extension operator You can expand the values in an array or object ; You can also collect multiple values as a variable
9、 Decorators @decorator It's a function , Used to modify the behavior of classes and even methods . Modifiers are essentially functions executed at compile time
10、class Class inheritance ES6 It's no longer like ES5 Use the prototype chain to implement inheritance , It's about introducing Class The concept
11、async、await Use async/await, collocation promise, Asynchronous processes can be handled by writing code that looks like synchronization , Improve the simplicity and readability of the code async Used to state a function It's asynchronous , and await Used to wait for an asynchronous method execution to complete
12、Promise Promise Is a solution to asynchronous programming , More than traditional solutions （ Callback functions and events ） More reasonable 、 Powerful
13、Symbol Symbol It's a basic type of .Symbol By calling symbol Function generation , It takes an optional name parameter , The function returns symbol Is the only one.
14、Proxy agent Using agents （Proxy） Listen to the operation of the object , And then you can do something about it