ES6 Arrow function

ES6 can use the arrow to define a function, note that it is a function, and do not define the class (constructor) in this way.

First, the grammar

1. Simple function with one parameter

var single = a + asingle (' Hello, World ')//' Hello, World '

　　

2. Need to use the parentheses before the arrows for no parameters

var log = () = {    alert (' No Param ')}

　　

3. Multiple parameters need parentheses, comma interval between parameters, e.g. two numbers added

var add = (A, b) = + A + badd (3, 8)//11

　　

4. The function body multiple statements need to use curly braces

var add = (A, b) = = {    if (typeof a = = ' number ' && typeof b = = ' number ') {        return a + b    } else {
   
    return 0    }}
   

　　

5. The object needs to be wrapped in parentheses, because the curly braces are accounted for as blocks of code.

var Gethash = arr = {    //...    Return ({        name: ' Jack ',        age:33    })}

　　

6. Direct as event handler

Document.addeventlistener (' click ', Ev = {    console.log (EV)})

　　

7. Sort callbacks as arrays

var arr = [1, 9, 2, 4, 3, 8].sort ((A, b) + = {     if (a > 0) {        return 1    } else {        return-1    }} ) arr//[1, 2, 3, 4, 8, 9]

　　

Second, the attention point

1. The typeof operator is the same as the normal function

var func = a = = Aconsole.log (typeof func); "Function"

　　

2. Instanceof also returns True, indicating that it is also an instance of function

Console.log (func instanceof Function); True

　　

3. This fixed, no longer fickle

obj = {    data: [' John Backus ', ' John Hopcroft '],    init:function () {        Document.onclick = EV = {            alert (thi S.data)//[' John Backus ', ' John Hopcroft '        }        //non-arrow function        //Document.onclick = function (EV) {        //     Alert (this.data)//undefined        //}    }}obj.init ()

This is useful, no more writing me,self,_this, or bind.

4. The arrow function cannot be used with the new

var person = (name, age) = {    THIS.name = name    this.age = Age}var p = new Func (' John ', $)//Error

　　

5. Cannot use argument

var func = () =>{    

　　

For 5, the test in Firefox36 is capable of outputting 55, seemingly without this limitation

Related:

http://kangax.github.io/compat-table/es6/

ES6 Arrow function