es6 Getting Started Tutorial

01-let.js

// variable var is not declared local scope 
// variable declaration is let local scope 
{
 var A =. 1 ; 
let B =. 1 
} 
the console.log (A) 
the console.log (B) 

// var may declare multiple 
// the let only once can be declared 
var m. 1 =
 var m = 2 
the let n- =. 1 
the let n- = 2 
the console.log (m) 
the console.log (n-) 


// var variable lift will 
// the let absent variable lift 
the console.log (X)
 var X = 'Apple'

02-const.js

// a value of a constant, constant change can not be declared const 
const PI = 3.1415 
PI = 3 // constant but a declaration must be initialized, otherwise it will error 
const UI

03- deconstruction assignment .js

// 1. Array deconstruction 
// Traditional 
the let A =. 1 
the let B = 2 
the let C =. 3 
the console.log (A, B, C) 
// ES6 
the let [X, Y, Z] = [l, 2,3 ] 
the console.log (X, Y, Z) 

// 2, the object deconstructing 
the let = {User name: 'Hello', Age: 18 is }
 // traditional 
the let NAME1 = the user.name 
the let AGE1 = user.age 
the console.log (NAME1 , AGE1) 
// ES6 
// Note that variables must be deconstructed and user attributes with the same name in 
the let {name, Age} = user 
the console.log (name, Age)

04- template string .js

// template string is equivalent to the enhanced version of the string with backquotes `, except as ordinary strings can also be used to define multi-line strings, you can also add variables and expressions in the string. 
// string into variables and expressions. Variable names written in the $ {}, {} $ JavaScript expression can be placed in 
the let name = 'GYY' 
the let S = `Hao are you $ {name}` 
the console.log (S)

05- declare an object abbreviated .js

name = const 'Perter' 
const Age =. 19
 // conventional 
const Person = { 
    name: name, 
    Age: Age 
} 
the console.log (Person) 
// ES6 
// Person in the name, age and must be defined attribute name, age same attribute can be abbreviated 
const PERSON2 = { 
    name, 
    age 
} 
the console.log (PERSON2)

06- shorthand method defined .js

// conventional 
const persons = { 
    name: 'GYY' , 
    Age: 18 is , 
    the sayHi: function () { 
        the console.log ( 'Hi' ) 
    } 
} 
persons.sayHi () 
// ES6      
// methods may be directly dispensed shorthand ' : function 'in parentheses to the general method of default 
const peropet = { 
    name: ' Dandan ' , 
    Age: . 19 , 
    the sayHi () { 
        the console.log ( ' haha ' ) 
    } 
} 
peropet.sayHi ()

07- expand the object operator .js

Person = the let { 
    name: 'Hi' , 
    Age: 20 is 
} 
// reference assignment change the value of the original object. Java memory reference and similar to 
// the let someone Person = 
// expand operator (...) for removing all the parameter object attributes can then traverse copy of the current object does not affect the value of the property of the original object 
the let someone = { Person} ... 
someone.name = 'Hello' 

the console.log (PERSON.NAME)

The default function parameters .js 08-

function Showtime (name, Age = 18 is ) {
     // to set the default parameters of the function, if there is no default parameter values are used pass 

    the console.log (name + ',' + Age) 

} 
// Showtime ( 'NiHao', 20 is) 
showtime ( 'nihaoya')

09- Arrow function .js

// the comparison is the first letter of the array size sorting 
the let ARR = [20,5,10000,80,30 ] 
the let of arr1 = arr.sort () 
the console.log (of arr1) 

// by size values to compare 
let arr2 = [20,5,10000,80,30 ] 
the let ARR3 = arr2.sort ( function (A, B) { 
      
    return A- B 

}) 
the console.log (ARR3) 

// arrow function 
let arr4 = [20,5, 10000,80,30 ] 
the let arr5 = arr4.sort ((A, B) => { 
      
    return A- B 

}) 
the console.log (arr5) 

// if the process can be simplified into only one sentence removed return 
the let arr6 = [ 20,5,10000,80,30 ] 
the let arr7arr6.sort = ((A, B) => BA)    // if the brackets can be simplified into only one parameter = A> BA 
the console.log (arr7)